2. Someone's ass with shit residue left over after taking a dump.
3. An insult given to someone who smells like shit.
Yo man, go wipe your nasty shit-ass
2. Also can refer to someone's ass, when covered in shit.
Jethro: Bill Bob come over here and help me plant some of these Bush for president signs over yander!
Billy Bob: I'm in the union, I'm voting Democratic.
Jethro: Well Shit! Yer nothin' but a shit ass demoncrat!
2. When I crapped my pants at walmart, everyone said I had a shit ass.