Stupidest thing I've ever done would have to be in the Enif Station mission. I was going for a wing of 4 NTF bombers. They launched bombs just before I shot the first one down. After I destroyed them, I went after the bombs. I was very close to them, and they were only a few seconds away from hitting the station, so I shot them all down at point blank range. Then I remembered my shields were out.

There was also a time when I fired an Inferno, missed, and it hit a nearby Rakshasa, taking out my shields. I couldn't see properly in the explosion, so I rammed straight into it....