Every Young Sheldon Easter Egg And Big Bang Theory Reference Explained

TVLine is taking stock of the many nods, cameos and crossovers linking “Young Sheldon” to its predecessor, “The Big Bang Theory.”

First launched in September 2017, the long-running prequel filled in the details of Dr. Sheldon Cooper’s upbringing in Medford, Texas. The story begins in 1989 and is told from the point of view of a more mature Sheldon, “who is older now and seeing his parents in a different light for the first time,” according to series co-creator Steve Molaro. That altered perspective allowed the spinoff to chart its own path, occasionally diverging from “Big Bang” canon without ever disrespecting what came before.

Whether you’re familiar with the prequel or simply curious, the following guide offers a robust rundown of all the ways the single-camera offshoot paid homage to “The Big Bang Theory,” answered lingering questions (for starters: what is a Bazinga?!), and painted a clearer picture of Sheldon’s relationship with his family — including his ill-fated father.

You’ll also find a wealth of Easter eggs, post-finale crossovers that unfolded after “Big Bang” ended in 2019, and new details about Sheldon and Amy’s future that were never disclosed on TV’s longest-running multi-camera comedy.

Laurie Metcalf’s real-life daughter, Zoe Perry, plays Sheldon’s mother Mary in the prequel.

Sheldon’s father, George Cooper Sr., is portrayed by Lance Barber, who previously appeared on “The Big Bang Theory” Season 5, Episode 11 as Leonard’s high school bully Jimmy Speckerman.

June Squibb originated the role of Sheldon’s grandmother in “The Big Bang Theory” Season 9, Episode 14. “Designing Women” vet Annie Potts took over the role in “Young Sheldon” Season 1, Episode 3.

In “Young Sheldon” Season 6, Episode 14, Georgie and Mandy’s daughter is named Constance — aka CeeCee — after her great-grandmother.

The “Young Sheldon” Season 4 finale planted the seeds for the family patriarch’s potential fall from grace, hinting at an extramarital affair between George and next-door neighbor Brenda Sparks. Seasons 5 and 6 continued to tease that something would happen, culminating in 13-year-old Sheldon’s spring break in Season 6, Episode 18 — the moment Sheldon later told Penny he walked in on his father with another woman.

In Season 7, Episode 4, the prequel revealed the truth: Sheldon had actually walked in on his parents — but would never learn that it was Mary in costume, not another woman.

Sheldon’s father’s fate was predestined — and “Young Sheldon” never sugarcoated it. George’s mortality first cast a shadow over the prequel in Season 1, Episode 3, when he suffered a minor heart attack. Then, in Season 4, Episode 17, Sheldon acknowledged that his father was living on borrowed time.

In Season 6, Episode 16, the prequel implied that George’s death would coincide with the end of the series — and that’s precisely what happened. He died off screen in Season 7, Episode 12, and his funeral was held in the penultimate installment.

Brenda’s son was established as Sheldon’s childhood bully in “The Big Bang Theory” Season 3, and referenced twice more in Seasons 5 and 9. He made his on-screen debut in Episode 1 of the spin-off, when he taunted Sheldon with his pet chicken, Mathilda. 

Ultimately, Billy was portrayed as more of a nuisance than a tormentor — and never shoved a Mexican peso up Sheldon’s nose, at least not on screen.

The boy genius was always loco for locomotives. The prequel’s first episode even opened on a close-up of Sheldon’s model train set. (“I’ve always loved trains,” Adult Sheldon said. “In fact, if my career in theoretical physics hadn’t worked out, my backup plan was to become a professional ticket taker. Or a hobo.”)

Sheldon loves to tell people that he has perfect pitch, which he discovered on Day 1 at Medford High. When music instructor Ms. Fenley — played by Melissa Tang, who previously guest-starred in “The Big Bang Theory” Season 9, Episode 2 as Mandy Chow — suggested that he pursue music professionally, the 9-year-old answered, “No thank you. Musicians take drugs.”

In the series premiere, we caught a glimpse of Bob Newhart’s alter ego demonstrating how to power a clock using only a potato — sound familiar? A signed photo of Arthur Jeffries also hangs on Young Sheldon’s bedroom wall. 

In Season 4, Episode 11, Sheldon tries — and fails — to make friends at East Texas Tech by starting his very own club in honor of the children’s TV personality.

Viewers less familiar with “Young Sheldon” may not realize that Dr. Cooper’s childhood best friend was introduced on the prequel — not “The Big Bang Theory.” Tam’s adult counterpart appeared on “Big Bang” in Season 12, Episode 4, where it was established that he and Sheldon lost touch after attending different colleges.

His first on-screen appearance was in “Young Sheldon” Season 1, Episode 2, and his final appearance was in Season 7, Episode 12.

Following five appearances on “The Big Bang Theory” as Nurse Althea Davis, Watson guest-starred on two episodes of “Young Sheldon” as Nurse Robinson. She has also played a nurse on two other Chuck Lorre sitcoms: “Two and a Half Men” and “Bob Hearts Abishola.”

Suffice it to say, Watson is the glue that holds the Chuck Lorre Cinematic Universe together.

In “Young Sheldon” Season 1, Episode 3, Sheldon declared that seeing 14-year-old Georgie behind the wheel of Meemaw’s car was enough to convince him that he never wanted to operate a motor vehicle — hence his reluctance when Leonard & Co. later tried to give him virtual driving lessons in “The Big Bang Theory” Season 2, Episode 5.

Tam is single-handedly responsible for inspiring Dr. Cooper’s weekly visits to Stuart’s comic book store, having introduced him to comics in “Young Sheldon” Season 1, Episode 4.

Long before Adult Sheldon explained to Penny why he had a designated couch cushion, Young Sheldon asked Tam to forfeit his seat in the Medford High cafeteria. (“It’s complicated. Just move,” he demanded in “Young Sheldon” Season 1, Episode 4.)

In “Young Sheldon” Season 1, Episode 6, Dr. Cooper revealed that his decision to pursue theoretical physics had nothing to do with unraveling the mysteries of the universe. He simply wanted to prove he was right to a condescending NASA employee who talked down to him during his freshman year of high school.

After sharing a piece of pumpkin pie with Howard in “The Big Bang Theory” Season 9, Episode 9, Musk made a cameo in “Young Sheldon” Season 1, Episode 6. The scene revealed that he found the solution for successfully landing a SpaceX rocket in Dr. Cooper’s childhood notebook.

Long before Sheldon explained the Schrödinger’s Cat thought experiment to Penny in “The Big Bang Theory” Season 1, Episode 17, he broke it down for George Sr. and Georgie in “Young Sheldon” Season 1, Episode 8.

Leonard isn’t the only one who’s had to put up with Sheldon’s timetable for bowel movements. It was referenced by Mary in “Young Sheldon” Season 1, Episode 8, and became a point of contention again in Season 3, Episode 16 (see above).

Two years later, in Season 5, Episode 16, Sheldon’s bathroom schedule was shown in full for the first time.

Our first glimpse of Sheldon’s “Star Trek” fandom came decades before he’d appear in a documentary honoring the late Leonard Nimoy.

In “Young Sheldon” Season 1, Episode 9, Shelly explained to Meemaw that “Spock is half-human and half-Vulcan [and] ashamed of his human side… That’s why I identify with him.”

Little did he know that he’d one day be gifted a Cheesecake Factory napkin containing Nimoy’s DNA.

Tam introduces Sheldon (and Billy) to Dungeons & Dragons in “Young Sheldon” Season 1, Episode 11 — a role-playing game he’d later play with Leonard, Howard and Raj, as well as Penny, Bernadette and Amy, in one of the 20 Best Episodes of “The Big Bang Theory.”

Long before Penny reluctantly sang Sheldon’s favorite childhood lullaby while applying vapor rub — counterclockwise, lest his chest hair mat! — Mary sang that soothing song to her germaphobic son in “Young Sheldon” Season 1, Episode 13.

In “Young Sheldon” Season 1, Episode 15, geology enthusiast Libby makes it clear that she sees Sheldon not as a friend, but as a kid she has to babysit. In turn, the boy genius sours on her chosen field of study, dismissing it as a “hobby.” (No offense, Bert!)

In the same episode, Mary tells Sheldon, “I bet when you grow up, you will be surrounded by lots of smart, wonderful friends,” to which he replies, “I can’t see that happening.”

Long before Amy crossed any T’s or dotted any I’s, 10-year-old Sheldon drafted his very first social contract in “Young Sheldon” Season 1, Episode 22. The Cooper-Sturgis-Tucker Behavior Agreement spelled out his role in Meemaw’s relationship with his mentor, Dr. John Sturgis. 

But wait — there’s more…

As Meemaw and Dr. Sturgis signed and dated the aforementioned document, the narrator revealed some rather gigantic #Shamy news: “I would go on to draw up such contracts throughout my life, with roommates, with my wife… even with my own children,” he said, confirming that Sheldon and Amy would go on to have kids (plural!) after the events of “The Big Bang Theory.”

Four years later, in Season 5, Episode 16, Sheldon mentioned that Amy eventually stripped him of his comic book allowance so they could start a college fund for their children.

In “Young Sheldon” Season 2, Episode 4, Sheldon attends a sleepover at Tam’s house, where he is first introduced to Mystic Warlords of Ka’a.

On “The Big Bang Theory,” Sheldon famously wears a T-shirt emblazoned with the number 73. In “Young Sheldon” Season 2, Episode 8, his younger counterpart establishes that 73 is his favorite prime number.

Jerry O’Connell was introduced as Georgie’s adult counterpart during “The Big Bang Theory” Season 11, Episode 23, when it was revealed that Sheldon’s older brother owned a successful chain of tire stores.

A few months later, in “Young Sheldon” Season 2, Episode 8, Georgie took a part-time job at Herschel Sparks’ auto body shop and discovered an affinity for tires.

“If it’s funny, it’s a Bazinga!” was the slogan for a novelty company introduced in “Young Sheldon” Season 2, Episode 10, which finally revealed how Sheldon came up with his signature catchphrase.

Mayim Bialik’s star-making role was referenced in “Young Sheldon” Season 2, Episode 11, when Sheldon’s twin sister Missy pitched a series of potential boyfriends for her Cabbage Patch doll.

MISSY: “How do you think Celeste would look next to Joey Lawrence?”
SHELDON: “I don’t know who that is.”
MISSY: “He’s Blossom’s brother.”
SHELDON: “I don’t know who that is.”
MISSY: “It’s a show. She wears hats.”

Little did Young Sheldon know that his sister was referencing his future wife. (Funnily enough, “The Big Bang Theory” also name-dropped Bialik three years before she was cast as Amy.)

Five years later, in “Young Sheldon” Season 7, Episode 12, Missy suggests that her brother will find a “smart, weird girlfriend” in California, to which he scoffs, “I have a girlfriend and her name is Science.”

Years before Sheldon forced Penny to ponder the question “What is physics?” and documented his findings, the pint-sized brainiac posed a similar experiment — using Missy as a test subject — in “Young Sheldon” Season 2, Episode 11.

“Bazinga!” might be the catchphrase most commonly associated with Jim Parsons’ alter ego, but “I’m not crazy, my mother had me tested!” is a close second.

Sheldon first alluded to that assessment in “Young Sheldon” Season 2, Episode 14, when Georgie asked his younger brother if he was crazy after confronting a bully.

“Young Sheldon” Season 2, Episode 22 tied directly into the series finale of “The Big Bang Theory.” On the same night that Sheldon accepted the Nobel Prize in physics, the prequel flashed back 28 years to reveal that he once invited his entire school to listen to the 1991 Nobel Prize announcements.

Unfortunately, no one showed. 

“In that moment, I felt like a neutrino, destined to be alone forever,” Adult Sheldon narrated. “Thankfully, I was wrong,” he added, as younger versions of his future friends appeared, one by one, amid a flurry of Easter eggs.

The asthmatic Leonard was seen in his signature red robe, with an inhaler resting on his desk.

Wyatt’s “little slugger” had a baseball bat near her bedside. A cowboy hat on the wall nodded to Nebraska, while a poster of Los Angeles suggested she already dreamed of becoming a star.

Howard appeared in his bedroom wearing his signature silk pajamas. Nearby sat a table of magic tricks and props. Mrs. Wolowitz also made a cameo, telling her son to “put away the fakakta game” and get to bed.

Howard’s future wife had a microscope on her nightstand, signaling her interest in microbiology. A trophy and sash nodded to her childhood days as a beauty-pageant contestant.

Raj was still in India. A stuffed tiger on his bed represented the Royal Bengal Tigers, while a telescope nearby foreshadowed his future career as an astrophysicist.

Sheldon’s future wife, seen in her signature nightgown, was up late reading her beloved “Little House on the Prairie.”

Years before a “Lord of the Rings” film prop threatened to tear him and his friends apart on “The Big Bang Theory,” Sheldon dove into the writings of J. R. R. Tolkien in “Young Sheldon” Season 3, Episode 4 — even dreaming that he’d transformed into Gollum.

TVLine was the first to confirm that Cuoco made an uncredited, voice-only cameo in Season 3, Episode 10, during a nightmare in which Sheldon was taunted by a bacteria-infested pool. She was the first of Parsons’ “Big Bang Theory” castmates to cross over to “Young Sheldon.”

It was during “Young Sheldon” Season 3, Episode 12 that the “hot beverage of comfort” became Sheldon’s go-to method for dealing with someone in emotional distress — “and it always worked,” he said. Well, “except when my wife was in labor, when it was suggested that I throw it in my own face.”

When George Sr. stumbled upon Sheldon making tea for fellow pint-sized genius Paige, he told his son that he was proud of him — all the encouragement Sheldon needed to stick with the method for years to come.

Sheldon revealed his favorite childhood meal — spaghetti with cut-up hot dogs — to Penny in “The Big Bang Theory” Season 3, Episode 20. 

In “Young Sheldon” Season 1, Episode 12, the pasta dish is established as Sheldon’s designated Thursday-night dinner. 

He later attempts to make it for himself in Season 3, Episode 21, before Mary serves it to the entire family in Season 5, Episode 4.

In “Young Sheldon” Season 3, Episode 16, Sheldon and George Sr. visited his future alma mater, Caltech. In the tag scene, father and son stood in the doorway of the cafeteria where Sheldon would one day convene with Leonard, Howard and Raj.

In “The Big Bang Theory” Season 2, Episode 1, a drugged-up Sheldon let slip to Leonard that Mary used to smoke in the family car. That habit carried over to “Young Sheldon,” when Sheldon’s mom was caught smoking in Season 3, Episode 21.

In “Young Sheldon” Season 3, Episode 21, Sheldon made a videotape to convince Mary to let him go to college. Behind him was a chalkboard whose writing mirrored the whiteboards used as a backdrop for Sheldon and Amy’s long-running web series.

In “Young Sheldon” Season 4, Episode 1, Jim Parsons was reunited with Mayim Bialik, who reprised her role as Sheldon’s wife, Dr. Amy Farrah Fowler, in an audio-only capacity.

But wait — there’s more…

In that same scene, as the Coopers gathered in the backyard to commemorate Sheldon and Missy’s respective graduations, Sheldon the Narrator (voiced by Parsons) said, “It was the best graduation party I had been to… until we had one for my son, Leonard Cooper.”

“I wanted his name to be Leonard Nimoy Cooper, but Amy wouldn’t let me,” he added. That’s when Bialik chimed in as Sheldon’s better half and said, “Be lucky I let you name him Leonard.”

In “Young Sheldon” Season 5, Episode 17 — aka the 100th episode — it was revealed that Leonard Jr. had taken up skateboarding, much to Shelly’s chagrin. 

Later, in Season 7, Episode 14, viewers learned that Jr. played pee-wee hockey for the Pasadena Penguins.

Sheldon’s mortal enemy was first referenced in “Young Sheldon” Season 4, Episode 11, when TV’s erstwhile Wesley Crusher — Wil Wheaton — caught Missy’s eye.

MISSY: “Wil Wheaton’s cute.”
SHELDON: “If you like him, you should watch ‘Star Trek’ with me.”
MISSY: “He’s not that cute.”

In “Young Sheldon” Season 4, Episode 13, a new tradition was born when Sheldon proposed a science-based car game to his mother: “I’ll say an element starting with the letter A, then you repeat that and add one starting with the letter B.”

As the narrator later explained, the tradition “would eventually bring countless hours of joy to Leonard on our drives to work. Much like my mother, he never beat me.”

Dr. Cooper first struggled to flash a grin in “The Big Bang Theory” Season 2, Episode 4, when Raj was profiled for People magazine.

In “Young Sheldon” Season 5, Episode 4, Sheldon again had trouble convincing George Sr. that he was happy having his own bedroom, separate from twin sister Missy.

In “Young Sheldon” Season 5, Episode 6, Adult Sheldon revealed why he’s always used an alternative word for sex. “Every culture has their taboos,” he said. “In the Ukraine, it’s rude to whistle indoors — and they’re correct. Not a fan,” he added, reinforcing his no-whistling policy first cited in “The Big Bang Theory” Season 2.

“In our society, any discussion of human reproduction seems to be so upsetting that it causes chaos,” he continued. “Even the word ‘sex’ provokes an uncomfortable reaction. I thought ‘fornicate’ might work, but that seemed too judgy.”

That’s when the 11-year-old reached for his thesaurus and landed on the perfect word — “a word so bland and clinical that it would be impossible to take offense to it.”

Helberg reprised his role as Howard Wolowitz (voice only) in “Young Sheldon” Season 5, Episode 7, which explored the origin of Sheldon’s “complicated relationship with engineering.”

After Teller recurred as Dr. Cooper’s father-in-law Larry in “The Big Bang Theory” Seasons 11 and 12, Penn and Teller made a cameo in “Young Sheldon” Season 5, Episode 22 as the dermatological duo Acne and Pus.

In “Young Sheldon” Season 5, Episode 22, Sheldon — on the precipice of adulthood — swapped his signature button-down shirt for his very first graphic tee: a red crew neck with a Flash emblem, not unlike the one he frequently wore on “Big Bang.”

In “Young Sheldon” Season 6, Episode 1, the Coopers arrived for Sunday service and took a seat in the back of the church — much to Sheldon’s chagrin. When Missy asked her brother what was wrong, he replied, “We’re nowhere near the acoustic sweet spot,” a preference first referenced in “The Big Bang Theory” Season 2.

It was established in “Young Sheldon” Season 1 that Georgie would be married by 19. “The Big Bang Theory” series finale told us that Sheldon’s older brother marries and divorces twice by the time he’s 45 — and the “Young Sheldon” spin-off is called “Georgie & Mandy’s First Marriage.”

In “Young Sheldon” Season 6, Episode 7, viewers were introduced to Mandy’s parents, Jim and Audrey, who run a tire shop that later employs Georgie. Will McAllister Auto & Tire ultimately become Dr. Tire?

In “Georgie & Mandy’s First Marriage” Season 1, Episode 22, Georgie and Ruben acquire the shop — and in Season 2, Episode 1, Georgie first floats the rebrand.

In “Young Sheldon” Season 6, Episode 22, 13-year-old Sheldon and his mother Mary headed to Germany so he could participate in a summer research program at the University of Heidelberg. 

“The Big Bang Theory” alluded to the trip in Season 1, when Sheldon told Penny that Mary accompanied him while he was a visiting professor at the Heidelberg Institute — though in that account, he said he was 15, not 13.

Also of note: Sheldon’s recollection of his time in Germany predated his later claim that George died when he was 14 — a line of dialogue delivered to Bernadette’s father in “The Big Bang Theory” Season 7 and now canon.

When Sheldon told Penny about his trip to Germany on “The Big Bang Theory,” he said that his mother flew back to Texas to help his dad after their house slipped off its cinder blocks. 

“It was tornado season, and it was an aluminum house,” he explained. 

But Sheldon’s memory proved a bit fuzzy: In “Young Sheldon” Season 6, Episode 22, it wasn’t the Cooper home that bore the brunt of the damage — it was Meemaw’s house that was destroyed in the storm.

Sixteen years after a brief (but memorable) turn in “The Big Bang Theory” Season 2, Episode 5 as a disgruntled DMV employee, Octavia Spencer appeared in “Young Sheldon” Season 7, Episode 10 as Meemaw’s probation officer.

Sheldon’s customary triple knock is first seen in “Young Sheldon” Season 7, Episode 12. (When Meemaw asks if that means she has to say “hello” three times, her grandson replies, “No, that would be crazy!”)

After lending his voice for 140 episodes of “Young Sheldon,” Parsons reprises his role from “The Big Bang Theory” in the prequel’s series finale. His scenes take place several years after the events of the 2019 series finale and reveal that the Nobel Prize winner has been hard at work on his memoir.

His home office is packed with Easter eggs, including Sheldon’s Nobel Prize, a framed photo of #Shamy in Stockholm, the DNA model, a Flash mug, a Rubik’s Cube coaster — and the couch from Apt. 4A.

After lending her voice in “Young Sheldon” Seasons 4 and 5, Bialik reprises her role from “The Big Bang Theory” in the prequel’s series finale.

In her scenes opposite Parsons, it’s confirmed that Sheldon and Amy have a daughter. Her name isn’t revealed, but we do learn that she shares something in common with Amy’s best friend.

“Your daughter wants to take acting classes,” Amy tells her husband, to which he replies, “I told you we never should have let Penny babysit.”

The final Easter egg arrives in the closing scene of “Young Sheldon” Season 7, Episode 14. Upon arriving at Caltech, Sheldon is approached by a professor who asks if he’s lost. He’s played by UCLA professor David Saltzberg, an experimental particle physicist who served as a scientific consultant on both “The Big Bang Theory” and “Young Sheldon” for a combined 18 years, after first being hired to consult on the unaired 2006 pilot of “The Big Bang Theory.”