I can imagine handlebars breaking or a wheel suddenly coming loose or a mechanical gearshift just ripping off because you were a dumb teenager and didn't realize that switching while going uphill is a bad idea. (had the pleasure of the last two)

But seatposts "apple-coring" riders through the saddle? What?

Or the chain springing out of the gear just while you're climbing uphill on the wrong side of a road next to busy traffic, and the sudden jolt throwing you off balance and making you sway into the traffic?