Similar to a donkey punch, but usually performed with a family member. The male has inbred sex with a 1st cousin or closer relation & as he ejaculates, punches said family member in the back of the head. In some cases, also followed with a Cleveland Steamer for good measure.
Q - What the hell is wrong with those cross eyed kids down the street?
A - Oh nothing, their mom just got Woodsfield Wallopped by her cousin Jim Bob.