It happened at a church camp. They had a homemade water slide going down the side of a hill. The other kids were going down it, and a bunch of them went off the sides, and ended up tumbling and sliding down the hill. I saw that, and wanted no part of that, knowing someone was going to end up getting seriously hurt (red flag).
My buddy tried to talk me into it, but I wasn't having it. As we were leaving, he mentioned something about getting on it halfway down the hill. I thought about it, thinking what would be the harm (another red flag). I agreed, and we got on it. My friend was in front, I was in back. As we started going down the slide, this turdburglar standing at the very top decides he's gonna come down. I told him not to do it, but dumbass come flying down anyway, and instead of opening his damn legs, his feet hit me square in the lower back, causing us to fly the rest of the way down to the pool at the bottom.
I stayed underwater for about a minute thanks to the shock. When I came up, I couldn't feel my legs, so I hung on the side of the pool. I threatened to kill the fool, even though I couldn't move if I wanted to. He left, I told my friend to go on ahead, so he left, and it was about 15 minutes before the feeling came back and I could move my legs again. My back was killing me, and my legs felt like lead weights, but I slowly made my way up the damn hill back to the camp. I managed to get cleaned up and changed for evening church service. Oh, I was so miserable. I didn't do anything at all the next day. The day after that I went home.
We all thought I had just bruised my back and hurt some muscles, so I didn't have it checked out. It eventually healed, and life went on. Over time, my back started giving me problems and kept getting worse until I had to get it checked out. Turns out I had herniated discs, deteriorated dics, and a gap in a vertebrae where it had split open (most likely from the impact). My body had tried to heal itself by filling in the gap with calcium deposits, which ended up pressing on some nerves. Surgery is not an option, since the doctor said there was a 75% chance of me being paralyzed if anything was done. Yay.
Short answer: stupid freak accident