Buttwings are small wings that can be found on the rear-end (butt) of something; they are generally found on non-existent things like Victini and anything that's free to buy.
Victini has a pretty prominent, but small pair of Buttwings that allow it to fly around and cheat the laws of physics.
Love handles are are not on the waist but above the butt so it looks like butt wings. They typically protrude over pants and are very obvious.
Damn, that bitch has buttwings!