bad stupid - forced a mare to go into a creek she didn't want to go into... turns out the bottom was VERY soft. The creek was partially iced over, mare went down, it took me and my friend about an hour to get her out (we were only like 16 years old), she was going into shock... we had to pull her out with another horse, bad situation.
Funny stupid... but still stupid. I was about 10 years old, my brother was 8, and my sister was 6. We attached one of those little red plastic wagons to our Shetland pony by tying it to his stirrups, and put my sister in the wagon. Turns out pony wasn't broke to drive. He did about 4 laps of the 20 acre field in like a minute. Our wagon was broken to pieces, as was the saddle. Luckily my sister bailed out of the wagon as soon as the pony first took off, haha!