Chalk me up as another person having been launched over the handlebars of a bike. The cause of said launch was, however, not front brakes this time, but rather me jamming my foot into the wheel. Why, you ask? At the time, my bike was approaching 10 years of loyal service and had, amongst other quirks, a loose front fender that would occasionally drag against the wheel to produce an annoying sound and slowing the bike down. I decided that, at full speed, it would be a good idea to gently kick it into place resulting in my foot getting jammed in the spokes and me flying over the handlebars and the bike landing on me a few seconds later. In hindsight I'm pretty amazed that I didn't have any pain at all afterwards. I went on to go to the indoor climbing wall that I was on my way to as if nothing had happened.
Although it isn't very stupid, mainly because I have no idea how I actually managed it, I dislocated (or something similar) my jaw a year or two back. If at all possible, try to avoid experiencing that. I couldn't open my mouth more than about a centimeter without incredible pain, which made eating an incredibly arduous process. In the end I had to go to my dentist, who couldn't do anything, it would fix itself. Randomly getting intense pain spikes while eating for a week sucks.
Finally, there's the story of my brother who was with me and my father at our grandfathers house where he had gotten hold of an old, forge-thing, I guess. (it's called an "ässja" in Swedish, I have no idea how to translate the word, and neither google nor wikipedia are being helpful) It's basically an open forge where you can get temperatures high enough to forge steel. Anyway, my grandfather thought we should try us some good old fashioned smithing, so we did. At some point, in a moment of incredible absent-mindedness my brother decides to take out the white-hot piece of steel from the fire with his bare hands. Two of his fingertips received third degree burns, but only in very small areas, fortunately.