I have two facepalm moments.
The first was in an older fort of mine, and this is the story I tell all my friends who are new to DF or who I try to convert. I had a really powerful Axelord- Legendary in Axes, a full suit of adamantine plate armor, etc. (this was before the 'fighter', 'dodge' etc. skills were around). She was the first of her squad to advance to the rank of Axelord, so I immediately replaced the old head of my military. Something important you should know about this dwarf- she had more children than a pack of Mormons. She would carry babies with her, caring mother that she was, and for whatever reason, they would follow her around once they could walk. This remained true through all the hard times I had, including the first siege of her career as my Commander-in-Chief. Like a good general, she led the charge against a group of about 15-25 goblins. Needless to say, she tore them to shreds. While the goblins were not able to hit her, they were able to hit her baby whom she carried into battle with what I'm guessing was her shield arm. The goblins not surrounding my war machine decided to destroy her other children. At the end of the day, I had a bunch of dead goblins, 7 dead children, and parts of a baby surrounding my poor Dwarven mother. She was devastated. Eventually, after about a season or two, she went insane from sadness and started killing people. By this point, the rest of her former squadmates had caught up with her in strength, so she went down pretty quickly. Despite her rampage, she was honored as a hero and received the largest of my tombs at the time.
The second facepalm moment is one that I encountered in this new build of Dwarf Fort, and I'm still not quite sure it wasn't a glitch. One of my dwarves went into a mood and claimed the Mechanic's workshop, of all places. He went back and forth with nothing but rocks. I watched for a bit and eventually got bored, because he was moving a LOT of rock, and put my attentions elsewhere. I didn't think anything of it, until I came back a few hours later to see him still diligently carrying rocks. I thought I had found a glitch, and that he was permanently stuck just carrying rocks in his mood. This was actually a good thing, though, because I had been forced to cut off access to the outside world due to about 3 ambushes and then a siege in the span of 40 minutes. Because I couldn't trade, I had very little materials with which 'moody dwarves', as I like to call them, could work with, so I had been losing dwarves left and right to melancholy, insanity, etc and was glad to not have to deal with that anymore. Eventually, to my great surprise, I received an announcement saying that my rock-moving dwarf had begun a construction! Once all was said and done, I got a mechanism worth about $2 million and engraved with just about every image you could hope to see. Here are some screenshots:
Value and Name
Description Page- it goes on forever.