This is a move when you have your girl get on her knees doggystyle and you stand across the room naked. then you put your hands together above your head and mimic a shark, all the while your humming the JAWS theme song. you make your way across the room and when you get near her you hump her as hard as you can sending her head crashing into the wall.
Q: How did you get that bump on your head? A: The boyfriend did the shark last night.