When I was 17 I had my first motorcycle, a Yamaha DT250 Enduro. I was sitting on it in front of my employer's office talking to a bunch of coworkers. I was revving the engine, and for some reason, just let go of the clutch. It was in gear.
Shot down the street doing a wheelie with my legs hanging off the pegs, arms outstretched holding on for dear life, looking at the sky. Somehow managed to pull myself up onto the seat, bring it back down to earth, and turn just missing running into the side of a building as the street curved.
At that point, I decided I'd better just keep on going, shifted into 2nd and rode home VS going back for ridicule.