wall ass
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.
Wall of ass
where someone has been farting in one room for hours on end, and when someone walks in the they get slapped in the face wit the wall of ass.
Fuck Darren have you shit pants again because i have just walked in a wall of ass.