Ass Chaff is the detrius which is flung against the bowl when you fart while shitting. Often acompanied by a loud bowl barker. Often your only hope of warding off a rump ranger or bum ninja ... in this case you hope bowl barking occurs.
1. Dude I blew some serious ass chaff from those taco's at lunch.
2. OMG Jim, I was so drunk last night when the resident ass bandit tried to rape me I couldn't move, luckily for me I was so scared I blew ass chaff when he yanked my shorts down. Otherwise ... I'd have been turdburgled