Well, it's a long list, but I thought of one.
It was when I worked at the Internet Archive, possibly 2009, when it was still in The Presidio, and not the church in Inner Richmond.
We were in an old office building, which had two main floors and a third, with a little eyrie. It was the best smoke break spot a workplace could offer. So, I popped up there one day for a break. But, I stubbed my ciggie out in a little nook of the wooden balcony, thought nothing of it, and headed out for lunch.
I can't remember where we went or what I ate, but I do remember getting back to the office, and the fire engine out the back. Everyone was calm, but it was also quickly obvious what had happened. You know when they say "my heart sank"? Well, I know what that is. I nearly burnt down the fucking Internet Archive.
First thing I did at the standup was apologise profusely, but not too profusely, and mean it.