Injury to the person executing the punch to the top of the skull.
well your half right... I am six foot(about). In my taekwondo class there was a man there who told me of the following experience: He was walking out the door of a room, when a man in the next room grabbed him by the hair (he had long hair) and went to punch him in the face, punching from over his head at a downward angle. Instinctively, he lowered his head and tensed his neck, so that the mans punch struck the top of his skull. The guy that told me the story said that the mans hand hardly looked human after that, while himself he hardly felt a thing.