Maybe you know the theme song by heart. Maybe you also know all the lyrics to soft kitty.
But did you know that The Big Bang Theory could have easily been a very different show? Or that two of the actors actually dated in real life?
Well, we've got a list of all sorts of fun facts about the show. Here are 14 things you probably didn't know about The Big Bang Theory.
Mayim Bialik has a PhD
Mayim Bialk, who plays Amy Farrah Fowler on the show, has something pretty major in common with her character. Just like Amy, Maykim Bialik has a PhD in neuroscience.
Dating in Real Life
We love seeing Penny and Leonard together on the show, and their chemistry makes a lot of sense. Johnny Galecki and Kaley Cuoco actually dated in real life, for about two years.
We could recognize Bernadette's high-pitched voice anywhere. To make that voice happen, Melissa Rauch does an imitation of her mother's voice.
A Very Different Show
The original pilot for The Big Bang Theory was completely different, adn the only two characters that were kept were Leonard and Sheldon.
The theme song for the original pilot as "She Blinded Me With Science" by Thomas Dolby. Can you believe the song by The Barenaked Ladies might have never happened?
Sheldon and Leonard's characters were named after actor and director Sheldon Leonard. The writers made the choice because they are fans of his work.
The Big Bang Theory uses a science consultant, David Saltzberg, who has a PhD in physics, on a regular basis to make sure they get the science correct on the show. He also sometimes gets help from Mayim Bialik.
Believe it or not, even though his character is totally obsessed with Star Trek, Jim Parsons has actually never seen an episode.
Raj's Character is Based on a Real Person
Raj, who in earlier seasons wasn't able to talk to women unless he was drunk, is based on one of executive producer Bill Prady's previous co-workers.
The Origin of "Bazinga"
Sheldon's catchphrase, "Bazinga" was inspired by on-set pranks. Writer Stephen Engel would say "bazinga" every time he pulled off a successful prank on his coworkers.
Though the writers have stated that they didn't create Sheldon's character based on Asperger Syndrome, actor Jim Parsons has said he plays the character as having those traits. Additionally, Bill Prady once stated, "Our feeling is that Sheldon's mother never got a diagnosis, so we don't have one."
We Still Don't Know Penny's Maiden Name
And it seems like we may never find out. At least that's what producer Steve Molaro says. We'll just have to keep guessing, or just think of her now as Penny Hofstadter.
A Different Amy Farrah Fowler
Actress Kate Micucci originally auditioned for the role of Amy Farrah Fowler. She was instead brought in later as Raj's shy girlfriend, Lucy.
The song "Soft Kitty" was a song that Executive Producer Bill Prady's daughter learned in preschool. The song was written in the 1930's by Edith Newlin. In 2015, The Big Bang Theory was sued for using the song without properly crediting Newlin.