A show like The Big Bang Theory, which has been on for 10 seasons and over 200 episodes, accumulates a lot of trivia. Here are 15 bits you can use to impress your friends or at least just make them go "huh, I didn't know that" -- unless you're a Big Bang superfan, in which case you probably did know some of these. But we'll bet you didn't know all of them!
1. It wasn't always called The Big Bang Theory. The original working title was Lenny, Penny and Kenny.
3. Mayim Bialik is the only actual Ph.D in the cast. She earned a doctorate in neuroscience from UCLA in 2007.
4. Penny wasn't in the original pilot. But a character named Katie (Amanda Walsh) was. The original pilot was never aired and was reshot to make the show we know today.
6. "Bazinga" is something writer Stephen Engel would say when he played a prank on someone. It made its way into an episode when Sheldon was playing pranks, and the rest is history.
7. There is only one set of stairs on the set. It just gets dressed up to look like different floors in the apartment building.
9. Johnny Galecki wears fake glasses that don't even have lenses in them. It's the old "glasses make you look smart" trick.
10. The show has a science consultant. David Saltzberg, who has a Ph.D in physics, makes sure the science is accurate.
11. "Soft Kitty" is an actual song. Co-creator Bill Prady first heard the song Sheldon sings when he's sick at his daughter's pre-school. It's based on an 18th-century Polish folksong.
12. Raj is (sort of) based on a real person. Bill Prady had a friend who couldn't talk to women when he was sober, not unlike Raj in early seasons.
13. Every episode is titled in the format of a scientific theory except the pilot. That one's just called "Pilot."
14. Bernadette's voice is very different IRL. Melissa Rauch based Bernie's high-pitched voice on her own mother.
15. Mayim Bialik and Jim Parsons learned to play instruments for their roles. Parsons learned to play the theremin, while Bialik overachieved and learned the harp.
(Full disclosure: TV Guide is owned by CBS.)