Swamp Muck

A shit stain from swamp ass.

When you are are suffering from severe swamp ass and engage in an impromptu sex session before your can shower. During sex, you leave a greasy, sweaty shit stain from your nasty, rank ass on the bed sheets, couch, chair, floor or other surface.

Swamp Muck is the dirty cousin of the infamous skid mark.

Rachel just put on fresh white bed sheets. She jumped my ass right after work and I left a little swamp muck in the bed from my swamp ass.