When some one gets hit so hard their legs buckle and eventually the reciever of the hit falls flat on his face.
Bob got jelly legged after Paul hit him for sleeping with his wife.
To hit a bitch on the crown of the head with the side of your fist. Your arm must make a full 360 degree revolution before making contact with the top of the head. This will not leave bruise because you are hitting on the top of the head where hair is located.
That pimp dokey konged his hoe after she didn't pay him.