The large stores of fat on the underside of the upper arms of older women. They normally make clothing ill-fitting and spill out of short sleeves. The common euphemism used by overweight women in denial is "butterfly wings." Considering their bulk, those wings will never fly.
Dude #1: Did you see that heifer shaking it at Matt's party last week?
Dude #2; Yeah, when she raised her arms she couldn't hide her granny hangers.