competition: Dumbest thing I did as a kid

When I was four my folks were at a wedding. As it came time to go they told me to go wait in the car. I did, and promptly fell asleep in the back seat. Unfortunately I had gotten into the wrong car.
Shortly afterwards the people who had rented the car got in and drove to the airport, unaware I was in it. They didn't find me until we got to the airport and they had no idea who I was. It took quite a while to sort it all out and find my parents.