a badunkadunk butt
A butt that moves in opposite directions, like one side goes up while the other goes down, and it looks like it’s doing a dance.
Her butt moves like it’s doing the cha-cha, and it’s the best part of the show.
I swear her butt moves like it’s got a mind of its own.
She walked by, and her butt did a full on badunkadunk, and I laughed so hard I got a stomach ache.