Mine was yesterday. (And a "thank the saints" moment, to boot).
Was testing out the new software upgrade, and working through a feature that we haven't used in the past - the ability to divide your world up into regions (so you can assign resources and customers and such, and work with smaller problems). The "previous administration" put us in one region called "TEST" (Seven years later, and we're still in TEST). So, I add two new regions, remove the original, click past the standard "you're deleting something" prompt.
And then find out that the region is the primary key for all the customers. And all the delivery information. And... pretty much *everything*. I suddenly have a very, very empty database.
The good news is that I had convinced the management that we really, *really* should have a test environment up for this sort of thing. But a year ago, that would have been the 24/7 "must be online" production system, and if I was really lucky, the backups happened the week before...