I SHd with boiling water from one of those kitchen geyser thing once when IP (in shitty kiddy loony bin - was told what a stupid thing to do it was, offered no treatment and told "I thought you wanted it to hurt?" when I asked for painkillers) - hand looked like an inflated latex glove 
Cigarette burns are worst, take ages to heal, but most of my cig burns aren't self-inflicted - were either done by another pt in same kiddy loony bin, or by this guy I met for sex a few times when I was 16, who liked to give me cannabis and cut my breasts 
I knew a girl once who burnt herself with lightees , GOK how.