A fat chick who wears short shorts or other tight, revealing clothing because she's convinced that she's hot. Feels the need to "strut her stuff," when really she's just making everyone around her queasy. A play on the word "badonkadonk."
Guy 1: Hey, you see that nasty girl over there in the tube top and hot pants? That's a major badonkadon't.
Guy 2: That's my mother.
Guy 1: ..............