To be deceitful intentionally knowing your actions will most likely cause negative reactions yet the "foul" selfish person does the deed regardless of anyone else's feelings.
Tiffany only went to graduation with my brother to hurt me. That bitch is always doin some foul ass shit!
The filthiest of the filthy. Foul refers to the smell of a filthy bitch / slut / skank-ass slut / or filth-a-ka-bob. This is the nastiest of the nasty of reeks.
Shut your legs, you're making this room smell foul you slut!