My endos were stupid learning experiences. My first was when I was a kid and wanted to hear the 'pingpingpingping' sound I figured my shoe would make on the spokes of my bike's front wheel

The latest was probably dumber... I was playing at doing trials stuff, and after doing a near-trackstand, I got going a little and tried doing a stoppie. Oh, I stopped alright. The back of the bike came up, I came off the saddle and was promptly straddling the top tube and handlebars with feet not quite reaching the ground. >< OHOHHHWWWOWWWWWW!!!

...uh... yeah. I looked around and made sure no one was there to see, then promptly scooted. Haven't tried THAT since!