Can’t say I have any interesting stories. Most of mine are just the head-scratching “I don’t know why that didn’t work; guess I need to reinstall” kind of story. Like enabling encrypted LVM on install and suddenly nothing is visible to UEFI. Or trying to switch desktop environments using tasksel and now I have a blank screen on next reboot. That lame kind of stuff.
My coworker though… he was mindlessly copy/pasting commands and did the classic rm -rf $UNSETVARIABLE while in / and nuked months of migrated data on his newly built system. He hadn’t even set up backups yet. Management was upset but lenient.