Your biggest Doh moment...

[BewareTheBarnacleGoose]

This was in SP, so no face-palming involved, but still some good :

Playing Rlyeh with a rainbow pretender. Had him cast twiceborn . Lost him fighting in friendly dominion, but he isn't back in the capital next turn. Set priests to call god. A few turns later, I get a message that "(my pretender) the wight mage drowned". Apparently wight mages can drown even though they are dead. I succeeded in permanently killing my pretender, since he dies if recalled to the capital