adjective: meaning a more that pleasantly plump woman, sometimes even grotesquely overweight. Not to be confused with Junk in the trunk, there is a difference in junk and nasty fat rolls that have been less than neatly tucked into the pants.
synonym: EW GROSS!
Jim: man, sarah is such a Fat Ass Bitch she should just die.
I girl with a fat ass and thinks she can show it off and who is a huge ass bitch to everyone and think she can talk to and steal every guy she first lays eyes on.