Lets just make this clear. This pierced the skin, could have been his leg or his back but it wasn't, it was his left cheek. Between the skin and the muscle... Sounds painful, very painful. Kinda like being torn apart internally.
I can hear his friends already saying, "Man, you are full of hot air"! Seriously, that sounds VERY painful, and he's lucky to be ok from the ordeal. I wish him a full and speedy recovery.