For 12 seasons, The Big Bang Theory taught viewers about science while making them laugh along the way. With Penny as the more relatable character, she acted as the on-screen viewer who was constantly amazed at the brainiac material her husband and friends talked about.

If fans wondered if Kaley Cuoco (Penny) broke character while reacting to her quirky castmates, she wouldn't be the only one. There have been oodles of BTS facts and bloopers that have come out since TBBT ended. YouTube has blooper reels showing fans how hard the lines are and how many times the actors broke character while trying to perfect the scene. With the cast and crew being so close, getting through a script was harder than anticipated because of the funny content.

Updated on April 25th, 2022, by Lynn Gibbs: As a sitcom, The Big Bang Theory has had some hilarious moments over the years that made the actors (as well as the live audience) giggle along. From Sheldon's "Bazinga" moments to Amy's obsession with Penny, there were plenty of moments that made the actors break character and ruin the shot. Luckily for fans, there are live takes on YouTube that show just how many times the cast broke when there was a funny scene, hard line, or accidental trip while filming in front of a live audience. 

Kunal Nayyar Couldn't Get Through This Line

In season 5's 'The Holographic Excitation,' Raj, Howard, and Sheldon ate lunch in Caltech's cafeteria. While Raj and Howard shared quotes that made their friendship the best, Howard didn't give Raj the attention he usually did in this scene. Raj was excited to talk about his Halloween costume but no one was interested.

While filming, multiple takes were had because the group of men kept breaking character. Once everyone got the giggles out of their system, Raj had a hard time saying "I was thinking of dressing up as Indiana Jones' mocha-skinned love child, Indian Jones."

An Off-Pitch Christmas Jingle

In 'The Santa Simulation,' apartment 4a threw a holiday gathering where they played a Christmas version of Dungeons & Dragons. At the end of the game, Howard, Sheldon, and Stuart had to ring a series of bells to the tune of "Jingle Bells" without messing up.

In the episode, the three men did a fantastic job and succeeded, but the bloopers told a different tale. The three men broke character when Jim Parsons and Simon Helberg rang their bells at the same time. Johnny Galecki went on with the scene but when he was supposed to grab his Santa hat, he accidentally grabbed Sheldon's stocking — making everyone laugh.

Fun Was Had During The Scavenger Hunt

In season 3's 'The Scavenger Vortex,' Raj set up a scavenger hunt for the group. He put a lot of effort into the scavenger hunt and wanted everyone to pair off. While Raj's relationships were his main storylines, his dedication to being a good friend should be noted.

When the group found themselves at the comic book story for the scavenger hunt, Leonard wished Penny luck and said "no hard feelings." As his partner, Bernadette was annoyed that he was being so nice to the other team. She shoved him and said "Hey, Romeo! Repair your relationship on your own time!" Funny enough, Melissa Rauch couldn't get the shove quite right and had to redo it again and again, making everyone break character with each friendly shove.

When Penny & Bernadette Took Anu To Dinner

In 'The Tam Turbulence,' Bernadette and Penny spied on Raj's potential fiance, Anu, to make sure she was the right girl for him. In the scene, the two women saw what she did at work before inviting her to dinner to get to know her better. While they first thought Raj and Anu were doomed from the start, over a few glasses of wine, the two realized that she was a total catch.

When Anu asked Penny and Bernadette what kind of guy Raj was, Kaley Cuoco (Penny) forgot her line and said, "Raj is like, so much fun to hang out with... No. I mean, he is, but no." Meanwhile, the live audience giggled at her blunder and Melissa Rauch (Bernadette) laughed with Cuoco.

Whose Line Is It Again?

In season 12, Sheldon and Amy's relationship timeline had them married and talking about thank you notes for their guests. But after Jim Parsons (Sheldon) said his line, no one chimed in after him.

The audience begins to laugh and Mayim Bialik (Amy) quietly looked off-screen and said "I don't know whose line it is," as an assistant ran on the set and gave Johnny Galecki (Leonard) his script. It was Johnny's line and he forgot as he laughed and cursed at himself before apologizing and redoing the scene.

The Spaghetti Was That Good

When Leonard and Penny's relationship timeline ended, things were awkward between them for a while. Sheldon, in particular, hated that the two broke up because he didn't like change and had already accepted Penny into his life. It was hard for him to be friends with both Penny and Leonard at the same time.

To prove that Penny still had love for Sheldon, she invite him over and made him his favorite meal — spaghetti with hot dogs. While filming, the two were in conversation but Parsons forgot his line. Cuoco didn't mind that Parsons messed up because she was mesmerized by the pasta. She kept eating throughout the scene and said "This tastes so good," while everyone laughed.

"What's My Line?"

In the episode 'The Peanut Reaction,' Penny was on a mission to throw Leonard his first birthday party. Leonard and his mom Beverly had some bad moments in their relationship, and one of those was never giving Leonard a birthday party as a child. Now as an adult, Penny wanted to make it to be special.

Sheldon didn't want to be a part of a party but Penny threatened to ruin one of his mint-conditioned comic books if he didn't help her. As Parsons explained the importance of a mint-condition comic book, Cuoco politely looked up and whispered "What's my line?" while Parsons laughed hysterically at her mistake.

When The Live Audience Chimed In

When Sheldon moved out of the apartment and moved in with Amy, their relationship agreement had to be amended. Penny and Leonard were thrilled to be on their own for the first time as Sheldon and Amy learned more about each other. To celebrate the moment, Leonard suggested he and Penny dance in their underwear, which they happily did.

However, while filming, an audience member said "ew" after Galecki said, "We are going to put on music and dance in our underwear." Both Galecki and Cuoco took the dig in good spirit and laughed it off while pointing the viewer to the door.

Snoring With The Giggles

When Sheldon and Amy spent their first night together in their new apartment, both were apprehensive about the change. This was a new situation for both of them and they were equally filled with nerves.

In the middle of the night, Amy woke up to Sheldon's snores. It was a combination of snoring and sighing while sleeping. Mayim Bialik did a fantastic job at keeping a straight face but the two actors eventually broke character. Even Parsons made himself laugh.

Howard Accidentally Tripped In The Scene

Howard and Bernadette's relationship timeline had its ups and downs but they were on a better page once they had their first child, Halley. While Sheldon thought a child would hinder their friendship, the two kept up with their social life by bringing the baby to Leonard's apartment. In one scene, Howard said that Halley was sleeping in the car seat and asked if he could place her in their bedroom.

On his way to the bedroom, Simon Helberg (Howard) accidentally hit the baby's car seat against the chair. This small trip made everyone laugh because of Helberg's nervous reaction.

The Iconic VapoRub Scene Made Everyone Laugh

When Amy came down with a cold, Sheldon used this as his chance to prove to Amy that he's a good boyfriend, and went out of his way to take care of her. Amy loved being adored by Sheldon so much that she pretended to be sick when she felt better. Getting Sheldon's attention was all Amy wanted, and though Sheldon was annoyed with Amy when he found out she was feeling better, he also understood.

In one scene, Sheldon applied VapoRub to Amy's chest in a very sweet, G-rated way. Amy, however, had been dying to be touched by Sheldon and liked it a little too much. It's no surprise that both Bialik and Parsons cackled throughout the scene because of their funny facial expressions.

Tears Of Laughter

In 'The Space Probe Disintegration,' Leonard and Sheldon were forced to follow their ladies around the mall because Amy and Penny were tired of always doing what the guys wanted to do. While the two men were waiting, they got into a disagreement about selfishness and their new reality of being in serious relationships. Now that Leonard and Sheldon were living with their significant others, it was emotional for them to leave each other. For Sheldon, it was one of the saddest moments because it meant change was inevitable.

While filming, Sheldon and Leonard were supposed to be crying but Parsons broke character and began laughing while dabbing his eyes.

Amy Couldn't Stop Laughing When Getting Spanked

When Sheldon realized that Amy wasn't sick and she made him take care of her for as long as he did, he decided the only way to get her to learn from her behavior was by spanking her. Amy, of course, didn't see this as a punishment and loved the idea.

Sheldon sat on the couch and asked Amy to lie across his lap, but as Parsons swat Bialik's bottom, her silly noises broke Parson's character and they had to redo the scene a few times. Their reactions to the scene were a moment fans loved about TBBT.