when a person's buttocks, usually a female's, does not curve at all. the ass region looks more like an extension of the back with a crack in the middle to allow for waste production. this flat appearance resembles a wall of ass.
Oh man, I put my hands down that chick's pants and it was total wall ass for miles.
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.