TIFU by biking

Obligatory "this happened a few years ago"

I was biking around my neighborhood and saw some guys biking around. By this point I'd never learned how to stand up and bike. I saw them coming up behind me while I was resting on my bike and knew I had to go.

So I stand up on my bike to look cool and I put too much weight on my left leg. I fall over, and I've scraped off about 5 square inches from my left knee. I can literally see the skin on the pavement. I got up and walked home.

The cut weeped and smelled really weird for a few weeks, and I still have a scar.

TL;DR: Tried to look cool on my bike, left my flesh on the concrete