Donkey tits are the mammory glands of a sloppy, thick bodied female. Generally the breasts of a swamp donkey. Donkey tits are generally the only redeeming quality of these husky heffers, and as such they will commonly be over exposed.
Guy 1: "You see that fat girl with half a shirt on"
Guy 2: "Ya, she needs to cover those donkey tits"
Guy 1: "Was that a swamp donkey? I just saw a set of donkey titties"
Guy 2: I donno, I didnt see her, all i heard was "HEE HAWW HEE HAWW"