What's the worst single line of code/script/command you have ever written/seen?

Mine was just before homework was due for a C++ programming course, and in unix, I tried to rename all of ”.cc” file suffixes to ”.C” using the following shell command:

mv *.cc *.C

(Can you tell I was self-taught on DOS 1.0?)

Anyway, that was five minutes before class… needless to say I got zero credit for that one. Six hours of my life gone.