Tire Tracks
When the human waste comes out too soon and leaves a brown "track-like" looking shitstain on the inside of your momma's panties. It can also be found on the inside of a toilet bowl when your bastard, son-of-a-bitch brother drops the bomb.
Son: Daddy what are the brown marks on mommy's underwear?
Dad: Wow your a dumbfuck, those are your mother's shitstain tire tracks.
Dad: Wow your a dumbfuck, those are your mother's shitstain tire tracks.