IT got it's name, by mimicking the sound an ass makes from a distance (when you check one go by, in slow motion, it goes, Badonk-a-donk).
2. n. The Badonkadonk, also known as the JL421 Badonkadonk, or just called "The Donk" is a land vehicle and "battle tank" created by NAO Design. (cite Wikipedia)
Also spelled badunkadunk.
2. The army may have the Badonkadonk, but Ninja has a better one.
Lady Cop: are you talking about my butt? umm
Dave: that is correct
Dave Chappelle: What is A "Badonkadonk"?
Asian Grocery Store man: Um a big penis?
Dave Chappelle: im sorry thats incorrect.