What is Ass-dirt?
The ring of dirt left around the toilet seat when a dirty ass person gets up off it.
Dude 1: "Man, can I use the bathroom at your house?"
Dude 2: "What's wrong with your bathroom?"
Dude 1: "I hate using it. My older brother always leaves ass-dirt on the seat."
Dude 2: "A.. that's just gross."