I have a stupid one, but far from funny… I’ve been using and building computers for a very long time so I’m far from a noob, but I’m still quite cautious, bordering on paranoid, so I like to unplug all other drives when re/installing an OS just to avoid stupid mistakes. I go through the installer on the livecd, there’s only one drive to choose from so I don’t think much about it, select that it should erase everything, I set up the new partition structure, and start the process. After about a minute I begin wondering “why is it taking so long?”, and “what is that ticking noise? SSDs shouldn’t be making any sounds when written to”, when I realize that I had unplugged the wrong drives and that I was currently overwriting my main storage drive. Of course I had backups of the most important things like photos and code, though not really synced for a couple of months so I lost some stuff permanently.