A sexual action, in which a part of a female's skull is removed, exposing the brain to open air. Then, a male places his genitals on the brain in a style often refered to as "teabagging". The action is highly discouraged as it usually results in death of the female.
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.
Guy #1: dude when she laid down I so planted my junk on her head and gave her a nicesweaty skullcap!