A friend of mine, former coworker, he installed a cron job with a custom python script on our prod ETL servers one time that took the entire app down. He misused the fileinput module in one line of code and essentially fork bombed the server. I forget the details, but if I remember correctly it overwrote a bunch of files with itself like a virus, and it would just continue executing itself until the box seized up. This cron job was supposed to run like every five minutes, so we had only that much time to troubleshoot wtf was happening after a reboot before the box dropped off again. Good times. He doesn't use fileinput anymore.