My first ATV, a 1987 Honda TRX350 4X4, had a twist throttle. I bought it from a guy with no thumbs (really) and he had it modified so he could ride it. One day I was loading it onto the trailer, which was connected to my Father's Ford Explorer. The throttle stuck as I was going up the trailer's ramps. When it did so I was thrown backwards, which caused my weight to shift. Holding onto the twist throttle when this happened resulted in WOT. The bike went up the ramps, across the trailer, launched off the trailer's headboard that bent forward from the impact and turned into a ramp, climbed the tailgate of the Explorer (busting the back window) and then proceeded across the roof of the Explorer. On the roof I abandoned ship - I jumped to the left, the bike went to the right, where it landed on its side. Nobody hurt, but the tire tracks were still on the roof of that Explorer when Dad traded it in...