Happy Frankenstein
The act of slamming your loved one's head into the head board/wall/tree/etc., during anal sex causing them to moan like a retard (thusly Frankenstein) also causing anal tension. A result similar to a donkey punch.
I give that bitch the nuttiest Happy Frankenstein the other night.

or

After I slammed that bitches head into the wall, I had that cunt moaning like a Happy Frankenstein.