A woman who has a nasty butt. Usually from being anally fucked to many times. Wide butt crack, jiggling all over the damn place, so lumpy, it looks like cottage cheese.
Yo, has anyone seen Paris Hilton's ass? She is such a nastybutt girl.
My mama call women who have jiggly butts nasty butt girls.
1a. dayem, that girl is nasty! (sexy voice)
1b. dayem, you is a nastygirl! (sexy voice)
2. dayem, that girl is nasty! stay the fuck away from me! (scared voice)