You know those days when you break a drill deep in a part, and you can't get a grip on the stub of the drill with pliers, so you try to save the part by clamping the drill stub in the vise so you can hold it and turn the drill back out, but instead the drill stub dents the vise jaws, so they're no longer straight and parallel?
Well, even if you don't, I do. Just wanted to share the joy.