@thegibson Accidentally crashed an IBM s/390 mainframe with nmap my first week on the job. Took down nearly the entire country infrastructure for a week. Still don't know why my boss didn't fire me. Or defenestrate me.

Killed a mail server by commenting out the tcpserver line in /etc/inetd.conf and took mail down for two days.

Misconfigured mod_proxy on a production box, half of China decided to download porn through it. Found out the hard way that the campus firewall had not, in fact, been installed a year previously. Even though I had a paper trail saying this was bad, I got punished for it because I was only a contractor.

Accidentally used in-house deployment software to uninstall the in-house deployment software in a production environment.