A thin, skin-tight hat piece.

the whale tail is the shape formed when a g-string rides up high over a womans trousers

A sexual position in which the receiver is lying down face up, the giver places his scrotum on the top of their head like a cap, with their penis going down over the nose, like the nose guard of a helmet, ending with the head in the receivers mouth.
Can also be done with the receiver sitting and the giver standing/squatting above them.

The act of shooting someone in the head in such a manner that the top of their head flips off like a cap.

NW DC slang for head, top piece, dome, suckin dick!!

slamming a chick from behind,and clocking her in the back of the head with brass knuckles right after you blow.