a form of self mutilation. you basically just rub an eraser over your skin really fast and it burns really bad and eventually the skin can break. it scars worse and hurts a lot longer than cutting yourself will, which is why for some people it works better. it gets the job done when mom finds out about the cutting.
My mom found out about me cutting and took away my razors. It's all good, though, she can't keep me away from pencils so there's always erasing.