A term shouted out when a bad or undesired turn of events takes place or something doesn't turn out the way you want it.
(man's arm is partially blown off in an explosion
Man: Shit n' biscuits!
Guy #1: Dude, I just saw your dog get hit by a car
Guy #2: What? Fluffy?!?!?
Guy #1: Yeah, I'm really sorry man...
Guy #2: Aw... Shit n' Biscuits!