Prank On A Female Victim
Sign up for an online dating service and use her name and photo if you have one. Then describe her as being desperate and horny. Be sure to leave her email address or phone number so any guy can contact her.

Bad Word
If you have a co-worker who leaves his cubicle to get a drink or smoke, then chances are he or she is also leaving their email or word processing software open as well. If they do this and are in the middle of typing something, go up to their computer and type the word 'SHIT' in the middle of their document. They will end up emailing it or printing it like that if they don't double check it.

Prank On Computer Illiterate
Stick a floppy disk in the floppy drive. The user will not be able to boot windows up until the floppy disk is removed.

Blind Carbon Copy Prank
This prank is for that annoying co-worker who is always sending out pesonal emails, chatting online with friends and using company time to talk on cell phone to boy/girlfriend. All you have to do is go to their email when they are away and set it to "send blind carbon copies" to your boss's email address.

Screensaver Password
Change your victim's computer so they need a password to get out of 'screensaver' mode.

Scrolling Marque Prank
Change your victim's screensaver so it is a scrolling marque and says something like "(victim's name) is gay and eats shit"

Bookmark Prank
While your victim is away from his computer, change all of his browser bookmarks so they go to porn sites or site with obscene material. Be sure to keep the title the same though, this way he or she won't know its changed until they click on it.

MySpace Computer Prank
Create a new 'fake' profile on MySpace claiming to be a new girl in school. Tell alot of boys personally where to meet her at lunchtime. Give each of them the same location and time. Then watch as dozens of boys go to the same location looking for a hot chick that doesn't exist.