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Rules The Big Bang Theory Cast Had To Follow On Set

There are many reasons why "The Big Bang Theory" has been hailed by the masses as one of the best sitcoms of all time. Not only does it show that there's more to nerd culture than just comic books and Star Wars, it also features some of television's most hilariously iconic moments. Over the course of the show's impressive 12-season run, the stars formed lasting friendships (and even one romantic relationship), which brought about a strong feeling of camaraderie.

However, while the set of the show was a very fun place to be for the most part, the stars also had a job to do, and so did co-creators Chuck Lorre and Bill Prady. Therefore, things couldn't always be carefree and light-hearted. In fact, there were certain rules that the cast of "The Big Bang Theory" had to follow to ensure a smooth filming experience, their physical safety (both on and off the set), and more.

They had to refrain from risky leisure activities

With another hit show on his hands, Chuck Lorre (the man behind "Two and a Half Men") felt the pressure of maintaining its success, he revealed in "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series." Therefore, when cast members of "The Big Bang Theory" partook in risky leisure activities that could've upended everything, Lorre set ground rules for the sake of their wellbeing and the fate of the show.

In September 2010, there were major concerns that Kaley Cuoco would need her leg amputated. Despite being a practiced horse competitor, the one that she was riding at a ranch north of Los Angeles got scared, causing Cuoco to fall to the ground. All was well until the horse then attempted to jump over her, but instead landed on her leg. "That was the darkest, most frightening time in all 12 years. Kaley could have lost her leg. It was a series of miracles that allowed us to get through that and for her to come out on the other end of that healthy," said Lorre.

Afterward, Lorre unveiled a set of rules, which were featured on the vanity card following Season 4, Episode 7 ("The Apology Insufficiency"), to ensure a similar incident didn't happen. The card states: "Following Kaley Cuoco's horseback riding injury, I've instituted new rules governing acceptable leisure activities for the cast of 'The Big Bang Theory.' 1. No friggin' horses. This includes those found on merry-go-rounds and in front of supermarkets." He went on to ban riding motorcycles and boating, among other more tongue-in-cheek things.

They had to sport their characters' iconic looks

Though their styles somewhat evolve over the course of the show's 12 seasons (like when Bernadette ditches her form-fitting cardigans in favor of looser button-down shirts after becoming a mother), the characters of "The Big Bang Theory" ultimately maintain their respective aesthetics, many of which aren't the most comfortable. This means that, for over a decade, certain cast members were forced to don restrictive clothing for the sake of their craft.

In "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series," Simon Helberg recalled needing assistance — and some butter on his legs — in order to pull up Howard Wolowitz's ultra-tight jeans. But the pants weren't the only aspect of Howard's look that caused Helberg discomfort: "And then to get all those sharp belt buckles so close to so many vulnerable parts, plus the tight pants, and the pin on my turtleneck that would jam into my neck... I was always trying to get used to being smothered by my own wardrobe."

Another cast member who suffered through a bothersome wardrobe was Mayim Bialik as Amy, known for her bulky, buttoned-up layers, knee-length skirts, and tights. She told author Jessica Radloff in her deep-dive book: "I was always sweating because Amy had so many layers on and didn't really have a sense of different seasons. It was always sweater weather for her, even when everybody else was in short sleeves or tank tops."

They couldn't make drastic changes to their appearance

Many of the actors who starred in "The Big Bang Theory" rock beards in real life, though their characters were clean-shaven. Therefore, if they grew one between seasons, it was shaved upon returning to set to maintain continuity. The only exception came when preparing to shoot Season 3, Episode 1 ("The Electric Can Opener Fluctuation"), in which the guys return from a three-month-long expedition at the North Pole with massive beards. They were actually asked to grow out their facial hair over the break, but fake beards ended up being used.

It was also preferred that they didn't do anything crazy to their hair, with the styles established in Season 1 becoming synonymous with the characters. Audiences came to know and love Howard's Beatles-esque 'do and Penny's long, blonde locks, for example. However, before they started shooting Season 8, Cuoco did the unthinkable — she chopped her hair into a pixie cut without telling anyone. In "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series," Cuoco said, "Something needed to shake up. I was bored and sick of the hair."

Chuck Lorre was shocked when he saw Cuoco's new hairstyle. For him, Penny's long hair was part of who she was. "The audience had become infatuated with the character, and not just the character's behavior and flaws and strengths, but in how the character looked," he said in the book. "They became iconic, and to disregard that audience attachment was a mistake. And I witnessed it first-hand. It would have been the same thing if Johnny [Galecki] had come to the wrap party and had shaved his head."

Practical jokes on set were banned

Just as Chuck Lorre forbade the cast of "The Big Bang Theory" from partaking in leisure activities that could lead to injury, he also banned them from pulling pranks on set after one that was attempted by Johnny Galecki and Kaley Cuoco went horribly wrong. While filming a dinner scene for Season 6, Episode 16 ("The Tangible Affection Proof"), the two planned to pull a prank that involved Galecki fake-punching Cuoco and her falling off her chair. However, when she got up from the floor, Cuoco was met with horrified looks rather than the laughter she anticipated.

Cuoco recalled the incident in "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series," telling Jessica Radloff: "I came up from the table saying, 'How fun was that?,' only to realize I had blood coming down my face as if I was in a boxing match." Turns out, Cuoco accidentally got hit in the head by the chair, which certainly wasn't part of the prank, and she had to visit a plastic surgeon to receive stitches. "The next day on set, there were all these signs saying things like, 'No more jokes! No more rough-housing!' I mean, we thought it was so funny, but no one else did." Director Mark Cendrowski had to strategically film Cuoco from a certain angle so that her injury wasn't visible on-camera.

They couldn't improvise lines

While the actors of some sitcoms like "It's Always Sunny in Philadelphia" were encouraged to ad-lib lines and discover what worked best, this wasn't the case with "The Big Bang Theory." Melissa Rauch, the actor behind Bernadette Rostenkowski-Wolowitz, told HuffPost Live, "'Big Bang' is very tightly scripted. Because we shoot in front of a live audience, it's basically like doing a filmed piece of theater, really." Plus, she and her castmates didn't often feel the need to put their own spin on things, as they believed the scripts was already top-notch: "I love it so much, but you don't want to mess with what they write because it's almost like this beautiful concerto that you don't want to mess up one note of."

Because "The Big Bang Theory" was tightly scripted, and because he had the most scientifically dense monologues to memorize, Jim Parsons wrote down every single line on index cards, which he always had with him. "There wasn't a set piece that didn't have my scripts or note cards in it," the actor said in "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series." It was only on a few rare occasions that dialogue was changed by writers during a taping. One such instance came while shooting a scene between Bob Newhart (who played Arthur Jeffries/Professor Proton) and Kaley Cuoco. When one of Newhart's lines wasn't landing with the studio audience, he suggested Cuoco say it instead. It was a move that proved successful.

They couldn't dress as Marvel superheroes

Halloween parties and San Diego Comic-Con are always highly-anticipated events for the guys of "The Big Bang Theory." Both give them a chance to embody their favorite pop culture icons through over-the-top costumes, the bulk of which are DC superheroes. From The Flash and Aquaman to the Green Lantern and Batman, their DC portrayals run the gamut. But why do they never dress as Marvel superheroes?

Both "The Big Bang Theory" and DC are entities of Warner Bros., which means that the studio already had the rights to DC imagery. Though no executives, showrunners, or cast members have ever spoken on the topic, securing licensing from Marvel characters would've likely been timely and costly, if it was able to be achieved at all. Due to its long and complicated history, getting licensing rights for Marvel properties is often tricky. For example, Walt Disney World is unable to build an Avengers Campus like its California counterpart because an agreement was previously struck with Universal Studios Orlando, which features Marvel Super Hero Island.

What's great is that the writers used the strong DC presence to build backstory. In response to a fan question asking why Sheldon loves The Flash, Steve Molaro responded, "Sheldon likes The Flash because, when he was growing up, he was bullied and picked on a lot. And The Flash is a superhero who's really good at running away." Still, this didn't prevent Marvel from being mentioned, with Stan Lee even making a cameo appearance in Season 3, Episode 16 ("The Excelsior Acquisition").

The cast (especially Jim Parsons) had to learn science jargon

From quantum mechanics to super asymmetry, the conversations had by the characters of "The Big Bang Theory" often revolve around science. However, the actors were largely clueless as to the meaning of the words in the script. Still, they had to make it sound believable. This was especially difficult for Jim Parsons, with Sheldon having the largest amount of jargon-packed monologues. An anxious person, Parsons recalled in "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series" by Jessica Radloff that he gave up drinking for the first nine years of filming to give his full focus to perfecting his intricate lines.

"It's not that anything got out of hand, but I knew that there was work ahead, and I wanted to be ready for it," said Parsons. Cuoco added, "I can't imagine the stress I'm sure the show put on him, because there was so much riding on his shoulders and so much to memorize. It was such a specific character that I can kind of see why he needed to put drinking aside. The show was 12 years of intense focus for him. That's a lot to take on."

Later in the series, when Sheldon begins dating Amy Farrah Fowler (Mayim Bialik), Parsons had less scientific dialogue to memorize, much to his relief. He said: "I had relationship stuff to talk about, and while Sheldon might do it awkwardly, it wasn't always a science hoop to jump through verbally."

They were tasked with staying humble

Aside from Johnny Galecki ("Roseanne") and Kaley Cuoco ("8 Simple Rules"), the rest of the original core cast members of "The Big Bang Theory" were virtually unknown in Hollywood. Therefore, when the show quickly took off and fans were clamoring to see them at their very first San Diego Comic-Con appearance, it was a mind blowing taste of fame that briefly went to the head of Kunal Nayyar (Raj Koothrappali). Co-creators Chuck Lorre and Bill Prady made it their mission to ensure that everyone stayed humble, calling Nayyar into their office for an important conversation.

In "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series," Lorre said: "The point of the meeting was to say, 'Breathe, slow down, don't make any big decisions right now.' And to remind him that the ensemble was everything. I said, 'Listen, God willing, this is a long journey, and the journey is one that should be made as an ensemble, not as here's my solo career. Don't leave the band and go off on your solo career so quickly!'"

The cast also helped keep each other grounded by escaping the hustle and bustle of Hollywood together. They enjoyed regular getaways at San Ysidro Ranch, located in the foothills of Montecito. Jim Parsons said, "We were able to do things like that as a group and not cause a lot of attention and just enjoy each other's company." They also bonded over their shared love of ping pong, which they played on set during breaks.

They had to promote the show

The cast of "The Big Bang Theory" had to promote their project via talk shows, junkets, conventions, and more, a requirement of any actor on a popular television show. Oftentimes, especially when they were asked to travel internationally, these press tours were a ton of fun and didn't feel like work. Johnny Galecki, Simon Helberg, and Kunal Nayyar have particularly fond memories of their promotional trip to Brazil.

In "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series," Nayyar said: "They figured out which hotel we were in, and hundreds of people showed up. We went out on our balcony and waved at everyone and said a few words. It was like being the Queen of England. I couldn't believe it, but I loved it because it was just an outpouring of affection and love these characters evoked in them. I found it very heartwarming."

Still, as nice as it was to feel love from fans of the show, doing press wasn't always so enjoyable. Galecki admitted in the same book that he often felt nervous speaking in front of people as himself and not having the fictional shield of Leonard Hofstadter to hide behind. He said, "I wouldn't sleep for two weeks before I had to do 'Letterman.' I always loved it after, because he's such a hero of mine, but that was especially nerve-wracking."

They had to perform in front of a live studio audience

Though many TV sitcoms have stopped using laugh tracks, roars of laughter can be heard during certain scenes on "The Big Bang Theory" because it was filmed in front of a live studio audience. On one hand, having a crowd present was helpful because instant feedback was received if something wasn't working. However, having fans present for certain iconic moments — such as when Sheldon smacks Amy's behind as punishment for pretending to be sick — added stress. Originally, the scene was supposed to take place off-camera. In "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series," Bialik said, "I was very relieved because doing that in front of people is so awkward. I think my mom might have been there, as well as my dad."

At the very last minute, it was decided that the entire scene should take place on-camera, in front of the audience. Parsons said in a discussion with The Paley Center for Media, "It was, I would say, one of the hardest things I've ever had to do because I found it tremendously amusing." He was also somewhat annoyed because, ever the perfectionist, he had no time to practice his facial expressions throughout the week. Director Mark Cendrowski told Jessica Radloff, "Jim and Mayim could not believe they were doing this, but they were so funny together. And the audience went nuts."

They didn't discuss their love lives

When Kaley Cuoco and Johnny Galecki began dating in 2008, the two made a self-imposed rule to keep their status private from the public — at least, for a little while. They explained in "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series" that they didn't want to ruin viewers' image of Leonard and Penny, who weren't an official item at that point. Given the fact that the rapidfire dissemination of news on social media wasn't what it is today, they were able to fly under the radar. However, after some time, their self-imposed rule — which was followed more closely by Galecki — began to take a toll.

"I think one of the things that created a chasm between us was my strict policies of privacy, and Kaley being very, very open about her life," Galecki said. "I was very uncomfortable with being public about it, and I think that hurt Kaley's feelings a little bit, and I can understand that. It certainly wasn't because I was embarrassed of her or our relationship, but I wanted to be protective of the audience's acceptance of Penny and Leonard, without distraction from the tabloids." They ended things after two years with nothing but mutual respect for one another, and remained friends throughout their time filming "The Big Bang Theory" and beyond. Galecki even attended Cuoco's wedding to Karl Cook in 2018.