A move in British football (or "
soccer") where the player directs a falling football by hitting it with his head. Since the only rule about making contact with the ball is that it cannot be touched with the arms or hands (except by the
goalkeeper), this is a commonly used move when a player is closely surrounded by members of the opposing team but needs to direct the ball to someone else. The cry of "On me head, son!" indicates that a player wants to head the ball.
It can't be good for the brain though, surely?