That sinking feeling when you realize that you somehow inadvertently deleted all your (non-hidden) files from your file server and they're gone now.

Until you figure that there were no modifications to those files since the last #backup run a couple of hours ago.
And it's just a one-liner to have them all restored from said backup.
And the worst thing that just happened is a bit off additional wear on the main platters of the fileserver.

Whatever it is, always have a backup.