Some time ago, it was common in Unix sites to have an NFS filesystem mounted on all machines that contained locally-built binaries to augment those provided by the operating system. At this site, we used a bunch of different platforms: OSF/1, Solaris, Linux, HP/UX, etc. So we had a large filesystem containing the source code, and built binaries for all the different platforms, and this included heaps of things, from Bash upwards.
A colleague of mine accidentally ran rm -rf on this filesystem.
It was taking a loooong time, so he realised and killed it, but not before it had removed a heap of stuff. Because this was something that could be rebuilt, it wasn't backed up, so we had to go through the process of downloading the tarballs, and recompiling everything for all the different platforms. It took a few days to recover most of it, and weeks to completely restore things.
The day after the incident, when he arrived at work, he found his keyboard was missing a few keycaps. It took him a while to realise that there were four gone: 'R', 'M', '-', and 'F' ...
