What is the stupidest thing you ever did as a kid?

That would depend on how old of a kid I was. I think it was pretty stupid to jump off the roof of the first actual house I remember living in, just because my brother thought it would be cool. No bones were broken when we jumped, but on reflection it seems like a pretty stupid thing to do. :)  

Oh a shorter list would be "what is the stupidest stuff I didn't do", lol

Grow up.

I went out the barn one morning while my dad was still in bed.  I got a can of used motor oil and I took it to my parent's bedroom and then I poured it on my dad's head while he was still asleep.

He wasn't very happy about that.

Stole money from the Catholic bookstore in 9th grade. Someone talked me into it. STUPID
Punishment? Ten swats on each of my hands with a razor strap.
And the principal was a big guy
With a very big belly...
...couldn't use the hands for two weeks
Yeah I learned a lesson

I didn't get into the really stupid stuff until I was a late teen / early adult. I was surprisingly cautious as a kid, it was a byproduct of babysitting my younger sibling.

The stupid? It usually involved intoxicating substances. Nothing I would admit to here. lol

Stealing cigarettes and aerosol items to get high.