FunFormat

This freeware screen saver is a great way to play a joke on your friend (assuming your friend knows what disk formatting is all about :-) ). If you set up FunFormat as the screensaver on your friend's computer, then whenever the idle time is up, FunFormat begins to imitate the formatting of the primary harddisk. It displays the regular disk formatting window, and advances its progress bar as if the formatting is actually taking place (This is imitation only! The hard disk is not disturbed during the imitation in any way!). If your friend closes FunFormat, an error message is shown about a missing operating system, but this is imitation, too: just let your friend close the message and the computer will continue to work as usual.