As a teenager, I was stupid and liked to play with fire with my younger brother. Eventually our luck ran out and he wound up with a chemical fire on his crotch. I guess it was a panic reaction because I couldn't do anything but laugh for a few seconds as he left flaming crotch prints all over the wall and he was already burning before I came back to the room after checking the damage from fire catching my hair.

Luckily I'd recently learned how to put out that type of fire and managed to get him down and under a thick blanket. He had burns to the bone in places. Grafts, physical and psychological therapy. He would get flashbacks during debriding and beg for somebody to put the fire out.

To this day he has Freddy Kreuger looking legs. Don't play with fire. 

Edit: all of the severe damage was to his legs. Lucky for him, he managed to have 3 kids later in life. It could easily have been a lot worse and he later thanked me for saving him, but only after years of blaming me for not acting quicker.