From Penny and Sheldon to supporting stars like Beverly and Mary Cooper, all The Big Bang Theory's heroes have one line that ...

In the second episode of The Big Bang Theory, Sheldon knocks on a door with a single knock, which is traditional. According to Fandom, his signature knock was not featured until the fifth episode ...

"The Big Bang Theory" proves one scientific theory in ... there was a reason why we were using the 'Young Sheldon' cast on it." The episode, which also features a guest appearance by Christine ...

There were tears, group hugs and even an emotional Sheldon on the Big Bang Theory set on Tuesday night (April 30) as the cast shot the ... to the show's fans. "Knock, knock, knock, thank you ...