A creative cuss word, better than mother fucker and way better than mother bitch. So vulgar while disgracing the name of mother. Almost like telling someone you fucked their mother's asshole last night but in a more nonchalant manner.
Crystal: I just wanted to let you know that you have sharted yourself while on the dance floor.
Becca: Seriously don't think you you're being a mother asshole telling me that? You could have waited until we were outside.