When a guy tucks his boner into his waistband in an effort to conceal it.

When a pussy buckles from a one knuckle love tap!

You shove a shoe buckle up your urethra. An act typically performed by "close" friends.

An "ass job", where a guy fucks a girls ass cheeks, without penetration, and in order to increase friction the girl will lower her belt down around her ass to squeeze her ass cheeks together to make it more pleasurable.

When you tighten your ass to the point where you feel immense pain.

Presenting one’s testicles through the fly of their pants; especially in an active endeavor

When you grab pull and twist a penis really fast