Not my mistake, but my buddies. He had a 70 Challenger with a 440, and he was always working on it. His parents house was up on top of a hill with a pretty steep driveway. He had his car up on ramps up by the garage and was working on it. It rolled off the ramps and down the hill where his dads camper was, one of those campers you put in the bed of your truck, so it was up on pipes that held it up so he could back under it with his truck. You guessed it, the car slammed into the camper, knocked it off the pipes and crushed the roof of his car. Needless to say, he was bummed to the max, and never did get the car fixed right.