I've been wracking my brain and I can't really think of anything incredibly stupid that I've done in my life that I would go back and reverse. Things didn't always work out, but I made the best choices with the info I had at the time. I'm generally a pretty measured guy who doesn't do stupid things.
I renewed HEAT tickets one year longer than I should have. That was dumb, I guess.
Talking to a guy who had season tickets during the 1-15 season ... remember? hahaha
I've done a lot of dumb things. I had a felony arrest when I was a teen but the dumbest things I've ever done I've seemingly gotten away with. We used to ride our motorcycles to the beach at well over 100 mph and run the center line because we "knew" cars would move over. Nothing beats fear and common sense like some good ole young testosterone.