When a man slaps (knocks) the head of his dick on top of the woman's clitoris in order to open the lips (door) to her pussy. Can also be applied to a woman's nose and her mouth.
Dick: Knock, Knock
Pussy: Who's There
Dick: I'm knocking on the door, open up!
Pussy: Cum on in.....
Pussy: Who's There
Dick: I'm knocking on the door, open up!
Pussy: Cum on in.....
by Mr. VanV August 09, 2011