An ass, generally in reference to a woman, that lacks curvature or "junk in the trunk." The ass is very flat much like that of an elephant in appearance.
Simply put, it's when the ass eats the pants. Usually happens when there is excess space in the seat of the pant, thus causing some fabric to be pulled inward into the colon area.
When a woman wears granny panties and her ass is so pancakey that her asscheeks hang under the thigh elastic and they flap behind her thighs like Elephant ears