I haven't done many reckless things but the first thing I thought of was the year I got a bike for Christmas when I was younger. A little while after that, me and my brother were riding our bikes around, and for some reason I thought it would be really, really fun to ride as fast as I could down a steep hill. It went about as well as you'd expect. I ended up going flying off the bike and smashing into the dirt. The weirdest part about the whole thing was that both me and the bike ended up completely undamaged. I still can't explain how that happened. XD

A few years later, I had a similar experience with sledding down a snowy hill and aiming for the snow ramp some people had built. Note to self: Stop going fast down steep hills.