A fictitious condition that is used to insult someone who's backside is straight as a board. The person the
joke is about usually is wearing
pants that makes them look like they have no ass at all. The person
may also end up with the nickname R.A.S. - Pronounced Rass.
Hey...
Hey, Dude! Look at that chick!
Yeah, man. She looks like she's suffering from Receding Ass Syndrome.
Sister: What do you want?
Brother: I just wanted to see how bad your condition has gotten, R.A.S.