Sheldon's Knock

Sheldon has a particular door knock ritual when alerting someone to his presence outside their door. Due to his obsessive compulsive tendencies, he must finish his knock, even if the person he's alerting opens the door before he is finished, in which case he will usually finish it on the door frame. His knock consists of three knocks before stating the person's name, and then he repeats this process twice: (knock, knock, knock) "Penny?" (knock, knock, knock) "Penny?" (knock, knock, knock...

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