The Big Bang Theory is famous for its successful blend of science and comedy. Much of its dialogue featured elaborate and, at times, complicated scientific principles applied to everyday situations. The show also included traditional humor, most times at the expense of its loveable and awkward characters.
Throughout 12 seasons, the show's cast delivered biting and clever remarks, a few of which rank as some of the most savage burns in modern television. Big Bang also introduced iconic and impossibly quotable lines that are now part of pop culture, cementing its place as one of the greatest sitcoms of the 21st century.
"Say, Cousin!"
The show loved reminding fans that Howard's first sexual encounter was with his cousin, Jeanie. He reveals it after eating drug-laced brownies, and his friends never forget it. They constantly remind him of it, further mortifying the future astronaut.
During the season 8 episode, "The Prom Equivalency," the group decides to celebrate a prom, and Stuart takes Jeanie as his date. Howard rapidly descends into a rage and even physically attacks Stuart. Raj gets the last laugh, though, as he takes one last opportunity to mock Howard's affair when he's taking the prom photos.
"... And As It Always Has ... Paper Covers Rock."
Rock, paper, scissors, lizard, Spock is an expansion on the classic game, invented by internet pioneer and blogger Sam Kass. It introduces two additional elements into the formula and first appears in the season 5 episode, "The Rothman Disintegration."
However, the game's most memorable appearance is when Sheldon explains it to Barry Kripke in the season 8 episode, "The Lizard-Spock Expansion." Kripke makes Sheldon explain the rules several times, and the oblivious Sheldon keeps going until Leonard tells him to stop.
"It's A Saturnalia Miracle!"
By far, one of the most memorable moments in the show comes in the season 2 episode "The Bath Item Gift Hypothesis." When Penny mentions that she has a gift for Sheldon, the physicist purchases several gift baskets to give to Penny, depending on the size and price of her own present.
When she reveals her gift is an autographed napkin from Leonard Nemoy, Sheldon loses his mind and gives her all the baskets. Then, realizing they're not enough, he gives her the biggest display of affection he's capable of, a hug. Both Leonard and Penny are pleasantly surprised, and Leonard declares it a Christmas miracle.
"Howard, You Know A Lot Of Doctors."
Poor Howard gets a lot of heat for being the only member of his friend group, aside from Penny, without a doctorate. He constantly mentions he has a Masters in Engineering from MIT, but that seldomly makes things better. One time, Dr. Gablehouser even dismisses the achievement by implying that everyone has one.
Bernadette earns her Ph.D. in the season 4 finale, "The Roommate Transmogrification," and she announces it to the group while at The Cheesecake Factory. Penny takes the opportunity to remark how Howard's the only one without a doctorate, making everyone laugh, even Bernadette.
"I Am Not Crazy. My Mother Had Me Tested."
Sheldon's eccentric personality often makes others think he has some sort of diagnosed condition. In the aftermath of his Nobel Prize win, President Seibert even encourages everyone at the university to describe Sheldon as "quirky."
Whenever his mental health comes into question, Sheldon denies having any diagnoses, revealing that his "mother had [him] tested." Mary confirms this in the season 5 episode, "The Rhinitis Revelation," although she also admits she regrets not following up with "that specialist in Houston."
"Is It Maybe Because, Like Sheldon's Work, Your Sex Life Is Also Theoretical?"
Bernadette is sweet but savage. In the early seasons of the show, she's still gentle and even naive, but she always has a tough side under the surface.
In the season 6 episode, "The Parking Spot Escalation," she delivers what is arguably the harshest burn in the entire show. When discussing Sheldon and Howard's fight over a parking spot, Amy and Bernadette quickly become angry and start attacking each other. Bernadette then insults Amy's intimate life, sending every jaw to the floor. Amy has a decent comeback, but it's Bernadette who gets the last laugh.
"Our Babies Will Be Smart And Beautiful."
Leonard becomes infatuated with Penny almost instantly. The two meet in the Pilot episode, and their relationship forms the core of the show's earlier seasons. After failing to retrieve her TV set from her abusive ex-boyfriend, Leonard and Sheldon return to their apartment, pant-less and humiliated. A mortified Penny then thanks them and offers to buy them dinner.
Undeterred, Leonard confidently declares their babies will be "smart and beautiful." Eleven years later, Sheldon reminisces about the moment during his Nobel Prize speech when Penny is actually pregnant with her and Leonard's baby.
"Bazinga!"
Sheldon first uses his catchphrase, "Bazinga!" during the season 2 finale, "The Monopolar Expedition." The word signals that whatever Sheldon said before is a joke, but usually, nobody laughs. Sheldon memorably uses it several times in the season 3 episode, "The Einstein Approximation," when Leonard tries to pull him out of a ball pit.
He last uses the word in the season 8 episode, "The Comic Book Store Regeneration." The show does not explain why he stops using it, but it could be because by that time, he already was more sociable and capable of displaying mediocre yet constant attempts at actual humor.
"He's A Little Broken, And He Needs Me. And I Guess I Need Him Too."
Professor Proton is one of Sheldon's greatest heroes. Arthur, however, finds Sheldon overwhelming and can't understand why Leonard puts up with him. During the season 7 episode, "The Proton Displacement," Arthur asks Leonard for help in a project. While they're working, he also takes the opportunity to question Leonard and Sheldon's friendship.
Leonard answers in a surprisingly earnest manner, stating that Sheldon needs him and the feeling is mutual. It's a beautiful way to describe a friendship that's not always clear to the viewer and one of the most wholesome moments in the entire show.
"Soft Kitty, Warm Kitty, Little Ball Of Fur."
"Soft Kitty" is Sheldon's go-to song for when he's sick. His mother used to sing it to him as a child and one of the fondest memories Sheldon keeps. As an adult, he makes his friends and Amy sing it to him whenever he's sick, and sometimes, he even sings it himself to others when they're sick.
Penny and Sheldon famously sing the song as a round in the season 3 episode, "The Adhesive Duck Deficiency." Amy also sings versions in German and Mandarin in the season 10 episode, "The Recollection Dissipation," and she apparently also knows how to sing it in Navajo.