when i was a kid, i saw my older brother and his friends ride their bmx bikes down a hill in our neighborhood. so i took my larger banana-seat bike up the hill and proceeded to ride down. i lost control as i went over a curb, then hit the front of the bike on some broken concrete. i flew over the front of the handle bars and slid chin-first on the sidewalk.
i fractured my jaw and got stitches.