Mine was last August or so. I thought it would be cool to jump my bike on this part of a sidewalk where the sidewalk was severely uprooted, enough that you could jump it without trying too hard. That part was easy. Landing on the other hand......

My head (no helmet) hit the ground first, after I went over the handlebars. Then, my bike landed on me. Me: probable concussion, a severe headache (bought a helmet shortly after this incident) and skinned up arm.. The bike: two tacoed wheels.

The impact nearly knocked me out (I saw stars) but when I came to I heard somebody in a car going by "are you ok!?" and I stood up, and threw my hands in the air, like I'd just won the special olympics or something.