badonkadonk, n. — Green’s Dictionary of Slang

badonkadonk n.

also badunkadunk

[? echoic of the buttocks slapping a hard surface]

(US) the buttocks.

2003		Keith Murray ‘Da Ba Dunk Song’ 🎵 Tina got a badunkadunk.
2009		Trace Adkins ‘Honky Tonk Badonkadonk’ 🎵 It’s so hard not to stare at that honkytonk badonkadonk.
2010		IOL News (Western Cape) 20 Jan. 🌐 Badunkadunk is a word that rapper Keith Murray invented for a girl with a big booty.
2016		C. Eble UNC-CH Campus Sl. Spring 2016.
2022		J. Hannaham Didn’t Nobody Give a Shit 222: Shakin their biggie-size badonkadonks in yo face.