the art of bashing the back of a chicks head in when shes going down on you. preferebly until she passes out. then you finish.
"dude, tiffany came over last night and started to give me head when i got an uncontrollable urge to bash her skull in. so i did, and she hasnt woken up yet. i think shes dead."
"i got myself into some hammerheading action the other day and now i can't read anymore."