Originally Posted by hu-man

Great jokes, thanks everybody!
Another good computer-related one:
If your victim has a fairly new computer with a Nvidia graphics card with new drivers, you can right click on the desktop and go to the nview tab... From here you can flip the screen, so that everything is reversed! It's impossible to figure it out if you don't know about that option, and your victim will have a real hard time undoing it, when his mouse pointer moves the direct opposite way than he thinks!