Not so much an odd fall, but a funny one. Maybe 15 years ago DH and I got crappy Schwinn mtn. bikes with nashbar-brand SPD pedals. After the first ride or two I found that the tension wasn't quite enough, so I asked him to tighten them JUST A HAIR for me.

Well, his definition of "just a hair" and mine differed. We got up to a stop sign and I couldn't unclip either foot. For what seemed like an eternity I was motionless, then said shitshitshitshit as I topped-over in slow-motion.