When someone's pants are so far up their ass it appears that their butt is actually munching on them. Things that can cause this to happen include: tight ass pants, extremely thin, silky pants, or sometimes just a big (or sometimes little) booty that has hasn't been fed i a while!
Homeboy 1: Damn bro, u see that chick, look at all that ass in those j-, whoooaaa, lol her pants tight ass a muthafucka!!
Homeboy 2: I know bro, "Say lil mama, why yo pants all up deep within the crevises of your ass??, You gotta Hungry Booty or something??"
Girl Walking By: Not anymore!!
*side note* (most girls wont respond so nicely lol)