I’ve done my plenty of stupid stuff, from dd disks I was using to forcefully uninstall dependencies of the package manager. But the one that takes the cake for me happened back in 2012, I was working at a research lab in the university and was sharing a computer with another intern. That other intern used Gentoo and so we agreed that the machine should be Gentoo, I’ve installed it at my house on my PC and got comfortable with it before we shared that computer. One thing that I learnt when installing Gentoo is that the /dev folder is created on boot, you don’t populate it when installing, instead you mount the one from the host system you’re using to install.
The computer had an issue with a device, can’t even remember what it was, so I thought I’ll run rm -rf /dev that should take care of the issue and after a reboot it will be repopulated… It might have worked, but what I actually ran was rm -rf /etc.