I had an old arch install about 7 years ago that stopped booting, so I booted into ubuntu, mounted the ssd, used a chroot to fix it, forgot to unmount the ssd, proceeded to rm the mount dir as it was "temporary". It took me mere seconds to realize what I did and by then it was a lost cause. I was able to use a file recovery tool to grab my precious memes, but thankfully there wasn't much else valuable on the drive.

Worlds most roundabout rm -rf /