5 Things You Didn't Know About 'The Big Bang Theory'

Amy (Mayim Bialik) and Sheldon (Jim Parsons) are actually playing the harp and theremin on the show. Both learned how to play the instruments after it was decided a harp would be Amy's favorite instrument.

(Source: THR)

Last October, Kaley Cuoco led the cast and crew in a giant flash mob set to Carly Rae Jepsen's "Call Me Maybe." Cuoco's sister, Brianna choreographed the entire thing. 

As a result, Briana landed a cameo spot on the Valentine's Day episode of "Big Bang Theory." She also choreographed another big scene on co-creator Chuck Lorre's other show, "Two and a Half Men."

Check out the flash mob here.

(Source: THR)

Anyone who watches the show knows Sheldon's (Jim Parsons) personal catchphrase "Bazinga!"  

Turns out Molaro uses the line as his own form of "gotcha" on set after setting up practical jokes behind the scenes.  

(Source: THR)

Anytime Sheldon becomes sick, he usually has Kaley Cuoco's Penny sing him the "Soft Kitty" song.  

Executive producer Bill Prady revealed it's a real song that came to light because of his daughter. 

"It's from my daughter's preschool in Sherman Oaks," said Prady. "It was from Australia and one of the teachers heard it there." 

The song has inspired shirts and stuffed animals. 

(Source: THR)

See ten more items from "The Big Bang Theory" here >

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