The Big Bang Theory is one of the most popular sitcoms of all time. Due to the success of the show, the main cast members made a considerable net worth, and their careers took a turn for the best. For instance, Jonny Galecki, Kaley Cuoco, and Jim Parsons were rumored to be paid $325,000 per episode during the first seasons of the show. But by 2014, the three were making $1 million per episode!

Starring in TBBT changed the cast's careers and lives for the better. But being on the show was no walk in the park. In addition to having to remember extremely complicated dialogues, the cast of The Big Bang Theory had to follow many rules, such as participating in crew-wide flash mobs between takes! One big rule they couldn't break was not growing their beards while filming.

Believe it or not, the reason why this strange was set actually makes sense.

The Cast of The Big Bang Theory Had To Take Lessons to Learn The Scientific Jargon Used In The Show

In order to play their roles, the main cast of The Big Bang Theory had to take small science classes to learn and understand better what they were saying in front of the cameras. Usually, assistants such as Dr. David Salzberg would come into the set to explain to the cast some of the more complex scientific explanations and jokes that had been written into the show.

The only cast member who played a scientist and didn't have to take these lessons was Mayim Bialik. It makes sense, after all the actress does have a Ph.D. in neuroscience. In fact, she would sometimes help the writers make sure they were writing actual things a scientist would say, instead of fake "sciency-sounding" nonsense.

For his part, Jim Parsons had the hardest time memorizing the scientific terms and jargon his character had to say. The actor would prepare for each episode by writing down his lines on flashcards. But that's not the only thing he used to do.

"I really just [run] rampant around my apartment saying these words, this dialogue over and over," Parsons told Fresh Air's David Bianculli.

"I'd go outside and say it. I'd sit down and say it. I'd stand up and run while saying it. Because I thought, 'I need to be able to trust myself to have these words come out.'"

It may seem like a lot of work, but we can see why he would do that. After all, his character had some of the most complex lines in the show!

The Cast Of The Big Bang Theory Weren't Allowed To Grow Their Beards, But Took Advantage When They Weren't Shooting

Have you noticed that none of the male stars of the Big Bang Theory ever grow a beard? This is not a coincidence.

As it turns out, the creators of the show prohibited the show's main stars, Jim Parsons, Johnny Galecki, Kunal Nayyar, and Simon Helberg, not to grow their beards while filming. The reason for this is that they thought that a beard would break their nerdy scientist look.

In between filming, the cast was allowed to grow their hair and even a beard as they saw fit, which Galecki and Helberg did on several occasions. But when they came back to the set, they had to shave to their nerdy look back again.

Although this rule was broken once. In the first episode of season three, titled "The Electric Can Opener Fluctuation," the cast is seen sporting long beards after being stationed in Antarctica for several months.

As it turns out, the actors actually grew real beards for filming this episode. However, they were told to shave them so that the make-up department could put fake ones on, although it was never stated why this decision was made.

How The Big Bang Theory Got Away With Changing Their Appearance On The Show

The cast of The Big Bang Theory wasn't allowed to change their look while they were filming the show so as not to affect their character's personality. That's why Sheldon kept the very same haircut throughout the show's twelve seasons! However, two actors managed to break this strict rule.

Firstly, Johnny Galecki refused to take off his glasses when they were rehearsing for the pilot of the show. Having Leonard use glasses was Galecki's idea. At first, the producers weren't sure about this, mainly because the lenses were causing issues with the cameras. But Galecki simply popped out the lenses and kept wearing his glasses, which proved to be a fantastic idea as these would become one of his character's most distinct features.

Later on, Kaley Cuoco shocked fans by ditching Penny's iconic long hair for a pixie cut. "I just cut my hair off and didn't tell anyone. I did it for an independent film called Burning Bodhi, and basically showed up to our Big Bang wrap party with short hair," the actress told Glamour.

"Chuck [Lorre] hugged me and said, 'Wow, look at your hair!' and I said, 'Do you like it?' I don't know if I was being rebellious. I mean, I did do it for the movie, which was my excuse to cut it. At that point, we were heading into our eighth season, and something needed to shake up."