Head over for For Men @ IGN.com and read up on their Pranks extravanganza articles.

Here's the link to
Pranks, Part II, and they've got their own link at the top of that document to Part I. It's all great stuff, I'm sure you'll find something relavent.
My favorite from their bunch, and harmless:
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Office Fun
At the win95/98 desktop open any program and restore it to its smaller window. Everything else on the desktop should look as normal. Now hit Print Screen. Open Paint, Paste, and Save. Now set the image as wallpaper. The application will look like it's still open. If you're feeling real nasty you can take a screenshot of the desktop as normal and after setting as wallpaper remove all icons and the taskbar.
Now this is good fun. Pranks that cause disorientation or confusion in the office are great because people usually try to keep their cool about them. To dismantle that is a bit cruel but can be very funny. Good luck.
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Ohh, that's good. I really have got to try that.
