Well, after a little thought, here it is.
Way back in 1972, I was a very young 18 year old. After I graduated from high school, I moved from Muskegon MI, to St Louis MO. While I was there I had this old Ford Wagon. Back then if your car wouldn't start, you could push it and 'kick' start it.
This guy needed a push, but didn't want his bumper scratched,
so we put a tire, with out a rim, between our two cars.
Worried that the tire would roll off down the road when the other car started and pulled away, I had the great idea of sitting on the hood of our car and holding on to it.
WHAT WAS I THINKING!
So........ as we pushed the other car down the road, I sat on the hood and held the tire, and when the other car started and pulled away, the driver of my car stopped, and whoosh! off the hood I flew, clutching the tire for my dear life! Luckily, I got a few good bounces on the tire, and didn't kill myself!
That had to be the stupidest thing I've ever done!
So..... what was the stupidest thing you've ever done!
Do a post and let me know.