Refers to the ass of a country girl. Know this booty by the "britches" or shorts that they wear that are usually too small and accentuate the booty of a white girl that would otherwise have no ass. This ass goes "Left right left" while in motion.
a guy sees a girl walk past who has an extra fine ass and says to his mate
guy-"i wouldn't mind putting my thumb in that"
mate-"yeah thats what i call a badonkadonk"