After my act of stupidity yesterday I got to thinking of other things I've done that seemed like a good idea at the time but were in fact not.
The last time I went skiing, I was in France and somehow ended up on an expert run (I was a mediocre skier, at best). Once I realized it, I couldn't turn back but knew I'd never make it down on skis either so I took them off thinking I could walk down. I took 3 steps, hit some ice, dropped my skis and slid some 20 feet on my butt. Another skier brought me my skis, muttered something about the "stupid American" and took off. I ended up putting the skis back on and it took me 4 hours to get down the run. I had ice burns on my face, a grapefruit sized bruise on my back and countless other bruises everywhere else.
What stupid thing have you done that you thought in the beginning was a good idea?