Sheldon wasn't always OCD about knocking on doors. On the fifth episode of season 1, he knocks on Penny's door without knocking and calling her three times.
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Things You Didn't Know About The Big Bang Theory
Hayran KurguHere are some mind-blowing facts that you probably didn't know about The Big Bang Theory.
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Sheldon wasn't always OCD about knocking on doors. On the fifth episode of season 1, he knocks on Penny's door without knocking and calling her three times.
