The Big Bang Theory recently ended its epic and unprecedented twelve-year run. The number of seasons and 279 episodes eclipses Married…with Children (259), Friends (236), and its sister show, Two And A Half Men (262) make it the undisputed longest running live-action sitcom of all time. The show predated the Marvel Cinematic Universe, Game Of Thrones, The Walking Dead, the DCEU, Stranger Things, and was at the forefront of letting geek flags fly high. The Big Bang Theory might have presented its leads as big-time nerds and even made fun of them at them and the culture’s expense. But it still found its way to the top of the heap of nerd culture.

For many fans, the show is a little divisive – it hasn’t been terribly funny in years and it’s pretty much the same nonsense every week, season in, season out. The series made stars and gazillionaires out of all of its leads. Blossom and Roseanne helped Mayim Bialik and Johnny Galecki out years earlier. But their names will now forever be remembered more for Leonard Hofstadter and Amy Farah Fowler.

Even more amazing (especially during these times), the show’s cast are all straight-laced. You never hear about any wild scandals or hot takes on subjects. Perhaps that’s because of the rules that the actors follow. Here are 12 Rules Actors Have To Follow (And 7 They Love To Break).

19 Follow: Crew-Wide Flash Mobs

For any fan that has said the show got a little long in the tooth over the last few seasons, the crew has been pulling off flash mob dance routines now for the past few years. Aren’t flash mobs too long in the tooth, about as long as that saying is?

But true enough, the cast and crew could be working on filming random episodes and then suddenly burst out into an elaborate dance number. Over the final seasons of the show, they seem to become a staple of filming and every now and again the numbers bleed into the show – Raj’s elaborate Bollywood number, anyone?

18 Follow: Super-Hero Outfits Are DC Based

In a show about a bunch of sci-fi fans, it’s a sure-fire bet that these characters would also be dedicated comic book fans. Over the course of the show, our heroes all have been at the comic store, thumbing through back issues and having hypothetical discussions about what superheroes can and can’t do.

While some of the conversations would include Marvel characters, you’ll never see any costumes or t-shirts come from the Mouse House Of Ideas. That’s because The Big Bang Theory is produced by Warner Bros. and that studio owns DC Comics.

17 Break: Don’t Talk About The Pilot

If one of the rules of The Big Bang Theory would be to not speak about the original pilot episode, then someone clearly isn’t listening to the rules. Otherwise, why else would we have all kinds of information on the original failed pilot of the series.

For the information that is out there, the original pilot featured a street-tough and street-wise girl, Katie played by Amanda Walsh. When the reception was less than lukewarm, The Pilot was rewritten, Katie was recast and renamed, and the show would take off into history.

16 Follow: Have To Promote The Show On Talk Shows

While this might seem like a no-brainer for some; it isn’t always obvious for others. But when the stars of the show are on their press tours for other movies and television projects, they better also have a few kind words for what put them on the map - The Big Bang Theory.

Whether they were promoting other things or not, the cast had to talk about the series on shows like Ellen or The Tonight Show. You’re getting paid nearly 1 million an episode, you can spend an afternoon here and there promoting the hand that feeds you.

15 Follow: Perform In Front Of A Live Audience

This is another one that might seem like a no-brainer, but it has been a long time that every sitcom was filmed in front of a live studio audience. Plenty of them are now filmed as single camera shows, as opposed to stage productions.

But The Big Bang Theory cast and crew spent the entirety of their run filming as a traditional sitcom. Which means rain or shine, sick or cranky, when it’s time to film the episode, the actors all had to be on their best game.

14 Break: Accept Lesser Pay

Over the years, many people and articles have compared The Big Bang Theory to Friends. Behind the scenes, the cast decided to embrace that notion and began to negotiate their salaries together as a unit. Prior to this, just Cuoco, Parsons, and Galecki earned the really big bucks.

While Sheldon, Leonard, and Penny were the core three of the series, the rest of the actors decided that they’re just as important to the show’s success. Instead of continuing to accept lesser pay, Kunal Nayyar, Mayim Bialik, Melissa Rauch, and Simon Helberg all pushed for more money and were backed by their costars. CBS gave them what they needed to continue the show.

13 Follow: Mayim Bialik Doubles As An Adviser

For the people that watch The Big Bang Theory AND actually understand all of the complex science that the characters talk about, they’re pleasantly surprised that it’s all real. Instead of just being fake “sciency-sounding” nonsense, the show hired several people over the years to advise the writers and set dressers on real concepts that the characters can riff on.

They got a two for one sale though on one of their advisers - out of all of the actors on the show, Mayim Bialik actually is a Neuroscientist in real life.

12 Follow: Openly Discuss Dating Life

Everyone knows that the stars are just actors and they have some modicum of private lives to head home to. But just like yourself perhaps, they’re not terribly interested in discussing their dating and/or married lives.

Although, a simple internet search would reveal certain facts about each actor. The most ironic one character-wise would be Kunal Nayyar, who plays a guy who barely can speak to women, being married to the beautiful Miss India Neha Kapur

11 Break: Openly Discuss Dating Life

While it’s easy to check out tidbits on The Big Bang Theory’s actor’s dating lives, two of the actors don’t talk about the fact that they once dated one another. Penny and Leonard themselves, Kaley Cuoco and Johnny Galecki dated for two years and didn’t tell anyone.

For fear of ruining fans’ perceptions of Leonard and Penny, they still never really discussed their relationship. Someone must’ve said something though, since it’s still the juiciest bit of gossip the show has ever produced.

10 Follow: Listen To The Show’s Fans

When any show starts, the creators think of the idea and it’s up to the stars to help realize that vision. But as the series takes off, all kinds of changes get made. That cast and crew of The Big Bang Theory made listening to its fans paramount.

“I’ve been really fortunate” to get that time, Chuck Lorre said in an interview with philly.com. “We got to learn about what the show was by doing the show, by making the show. The show taught us what it was. The audience taught us what it was.”

9 Follow: Learn Science Material

Other than Dr. Mayim Bialik, a lot of the scientific terms, concepts, and theories might seem like a foreign language to the rest of the cast and crew of The Big Bang Theory. But not only as professionals are they able to pull it off to perfection.

The reason the cast can pull off some of the more complex scientific explanations and jokes because they have assistants on call to assist with the science of the show, most notably Dr. David Salzberg.

8 Break: Sheldon Has Aspergers

Not necessarily a rule per se, but anyone familiar with people who have Asperger’s syndrome might instantaneously think Sheldon has lived his whole life with the affliction. The producers of the series always denied that Sheldon has Asperger’s, or any other type of Autism.

However, Sheldon himself, Jim Parsons he does believe Sheldon has Asperger’s and portrays him as such.

7 Follow: Have To Wear Character’s “Uniforms”

One of the many reasons that The Big Bang Theory is one of the most iconic sitcoms ever is the iconic looks of all of heroes. Much like the superheroes they idolize have iconic costumes, each member of the cast has a look iconic to their characters.

Sheldon wears superhero logos and math equations, Leonard wears hoodies, Howard has fancy belt buckles, and so on down the line. Penny is the exception to the rule. Perhaps because she isn’t an orderly scientist like her friends; she also has no discernible costume, unless you count spaghetti strap tank tops.

6 Follow: Give Props To Their Audience

Without the fans of the show, there probably isn’t a series at all. Thanks to the show’s massive fan base (18.5 million watched the finale), the series was able to fun twelve years and got to go out on top.

The stars of the show know exactly where their bread is buttered – the fans. The Big Bang Theory loves to pay tribute to their fans, whether it’s in their interviews paying lip service or performing elaborate dance numbers during tapings, the cast’s love affair with their fans has been one of the big reasons it lasted for so long.

5 Break: Raj Needs Drinks To Talk To Women

During the early days of the show, it was established that unless he was drinking an adult beverage, Raj couldn’t speak to women at all. Even when the girl was just a girl and not a girlfriend – like Penny.

This rule was only broken seemingly one time. Towards the end of season one’s “The Dumpling Paradox,” a script supervisor clearly wasn’t paying attention. Raj was able to speak about playing video games with Penny in the room. It wouldn’t be until years later that his Selective Mutism was cured.

4 Follow: The Show Ends Without The Core Three

While every character on The Big Bang Theory is as important as the next, Penny Sheldon, and Leonard are the core three characters that the show was built around. Every other character on the show stems from their world.

Which is why doing the show without any of them would have been a devastating blow to the series. So, why bother? Once Jim Parsons made the decision to not continue to the show for what have been two more seasons, the producers decided to go out on top rather than soldier on without its star.

3 Break: An Alternate Reality From Young Sheldon

Young Sheldon tells the story of our favorite theoretical physicist growing up in East Texas. But does the show take place in the same universe as The Big Bang Theory? How could it? – the guy starring as Sheldon’s dad is the same actor who played Leonard’s bully growing up!

In a show where the characters definitely subscribe to the multiverse theory, this could have been a comedy goldmine! But instead it just seems like a casting agent didn’t seem to mind, and neither did Chuck Lorre.

2 Follow: The Guys Have To Shave

With the exception of when the boys were stationed in Antarctica, they have been clean shaven for every single episode. That helps to maintain their iconic looks and feels of being nerdy scientists.

However, have you seen some of them in public?! The boys like to look like gruff and bearded manly men. Johnny Galecki and Simon Helberg both have huge beards when not in character for the show.

1 Break: Sheldon Finally “Gets It”

For 269 episodes – 134.5 hours, Sheldon Cooper seldom understood anything about anyone. While he might have tried to for science – sake, he also never seemed to care about any of his friends’ true feelings unless it pertained to him in some way shape or form.

That all changed in the final moments of the entire series. When accepting the Nobel Prize he worked his whole life to get, Sheldon realizes the error of his ways and genuinely thanks his friends and in the most touching of ways asks them all to stand and be acknowledged for tolerating him and helping him become the person he became.