(n). Pants that sag in the butt area causing what appears to be a diaper like appearance.
Excess fabric in the butt area, that is not filled out by the butt of the wearer.
This problem frequently occurs on girls who have no butt and are wearing pants that leave room for girls who do. The pants are usual a cotton material, and are not form fitting. Diaper butt usually causes feelings of self-consciousness and embarrassment. Diaper butt is not desirable and is extremely unattractive.
Girls say: "Do these pants give me diaper butt?"
Guys would say, "Oh man, did you see that girl's diaper butt?