An act in which two nude men stand facing one another, approximately eight inches apart, and swing their hips in such a manner that the hats of their flaccid penises slap together repeatedly. A third party can be introduced, however, the body motion must be changed to vertical.
There's fucking nothing going on tonight. Why don't we just slap hats?
The type of style where one wears a baseball cap slightly off to the side giving the appearance that he has just been slapped upside the head. Style is generally worn by today's younger crowd.
My daddy didn't like my boyfriend because he thought he looked goofy with slap hat.