Once when I was a teenager I got a lift home from a party off someone who was over the limit by quite a long way. I was in the front, wearing a seat belt.
After they dropped me off my mate got in the front and didn't put his seatbelt on. Five miuntes later they were half way back to the party and attempting handbrake turns, naturally.
When they inevitably flipped the car my mate in the passenger seat was flung into the back of the car. If he was wearing his seatbelt he would have been crushed.
I realise that I didn't come very close to death here, but y'know, I bet some of you have, so go for it.