Similar to the phrase "D'oh!", pulling a "tuxford" generally means that you have done something totally moronic such as rebooting a live server with 50k odd users on at the same time instead of the testing server you THOUGHT you were rebooting.
What makes a "tuxford" different from a "D'oh!" is that you have to reboot the live server with a 60 second notice to save your work instead of a 30 minute notice, AND cancel the shutdown before it actually happens. If you accomplish a tuxford, expect constant and endless ridicule over your server administration skills, endless memes using your name amongst your user base, and including having your name used as an urbandictionary.com entry.