My Funny Picture - What are some of the best computer pranks ever! Non downloadable stuff?

What are some of the best computer pranks ever! Non downloadable stuff?

Pranks that are really really funny which you can on any computer. Even in school.

close everything so just the desktop is showing. push the printscreen button which takes a picture of it. then set it as background then hide the icons and bottom tool bar and it will look like its there and when they try and click on it, it wont work. i did that to one of my friends a while back
A friend of mine switched the mouse and keyboard wires around on two computers in a college computer lab once. A girl sat down at one and freaked out because her computer opened Word by itself and started asking her questions... It was really just my friend at the computer next to her typing it..
I made a fake boot screen and set it as a desktop item NOT a background. Its an animated gif and looks like your computer is stuck at the boot screen where the blue strobe keeps going. I also made a fake Vista and a XP screensaver animated gif too. Fake Boot> http://img86.imageshack.us/img86/9718/windowsxpboot1js0.gif Fake XP Pro.scr> http://img86.imageshack.us/img86/1686/xpproscrqx3.gif Fake Vista.scr> http://img86.imageshack.us/img86/7850/vistascr1oo0.gif You can replace some of the default windows sounds with some recorded whisperings and that will freak someone out.
do what daniel said ...it would totally piss someone off....but very funny