Apendicitus. My appendix was around 45 minutes from bursting when they took it out.
A particularly rough journey in the bay of biscay. My boat capsised, and if it wasn't for the weighted keel, we wouldn't have turned back over and we would have filled with water. Naturally, the waves were 5 metres high. I've actually got a video of it somewhere :)
Suffered from my heart literally doubling, then trebling its speed. The pain was so intense, I froze like a statue and could not breathe. I still haven't told anyone about this yet.. I should get around to it.
Sand dune collapsed when I was doing a front flip off it, landed on my chest, got whiplash to my back, and it hurt like forget. I couldn't breathe after landing on my chest, lucky my friend was around and got me breathing again.
Oh, and some nackers were running around town with hurls and causing havoc, so when I told them to forget off to their cousins house for some nice incest love, they threatened to beat me up. My group of friends was close though, and they backed off. Still, those people will actually try kill you. Only they're all as weak as piss :)