Well, I can't hold a candle to @cryptkeeper17, but here's one that I can remember fairly recently.

Last spring our foreman retired and we got a new foreman from town that has been doing road maintenance since 1983. We had a pretty big slide that covered the highway and it dropped the road at the top of the cliff a few feet.

I was working at the top with the contractor in the excavator and the foreman was nowhere to be found but had told the gravel truck driver to dump a load of armour rock where we were working so the excavator could place them at the bottom of the culvert flume. I just took control and told him to dump them where I figured it would be easy for the hoe and safe for him to dump.

I was pretty proud of myself for not needing the foreman there and just taking control of the situation.

Until the foreman showed up and asked why the driver would dump the pile right there. I started to feel sick as he went on about what a dumb place to put them and whatever else he was saying. I was too busy trying to figure out how to word it so I just blurted out, "I told him to dump it there. We tried to call you, but you didn't answer so I thought that was the best place."

I didn't apologize and then he asked me what I was thinking. I told him my thought process and asked where he would have wanted it. He showed me, and explained why. I took it into consideration, all the while internally smacking my head for a very poor first impression with the new boss.

One good thing came out of it though, the trucker was impressed that I admitted fault and didn't hang him out to dry, and he said as much.