HEY! You rearranged the keys!!! YOU BITCH!
It's amazing how many people think they can touch-type until they sit down at a computer with its keys rearranged. You can also spell disturbing things with the letters. You'd be surprised at the types of things you can still spell with only one of each letter. Once I spelled "SPICY BUNGHOLE FART" (and then just stuck the other letters where spaces were left). A minor variation would be to just switch a couple of the keys and see if people get frustrated, or just put one very short strange or dirty word into the keyboard where it doesn't belong. Keys are usually pretty easy to pop out and stick back in.
Another really good one that usually gets even the pros is to make a fake desktop. First, hit the "print screen" button on the person's keyboard. This "prints" the desktop, just how it looks to your eyes, onto your clipboard. Then you can paste the image into a picture editor, and save it as a bitmap (.bmp file). After that, what you'll need to do is put all the icons in the recycle bin and rearrange the ones that can't go in there. THEN set the new bitmap you just made as the background! It will LOOK like there are icons there when they are only pictures of icons. Now watch the person try really hard to click something that isn't there. MWAHAHA! (Don't do this to people who will kill you for messing with their computer layout, and make sure the icons can be retrieved!)
And here's a fun computer prank suggested by Jason V.:
Make the screen look like a "blue screen of death" by opening a text editor, turning the background black and the text white, and expand the borders of the screen to make the drop-down menus and whatnot disappear. Then type your own Blue Screen of Death message, but add something strange to the end; Jason suggests "Ha ha, I ate your file, jackass. Shoulda bought a Macintosh." (Unless you're a real jerk, you'll want to make sure whatever they actually were working on is saved, because they may try to restart when they see this screen.)
Also, try some of these funny computer pranks to download on their computers:
bad_day: This is a program that, when activated, turns whatever's on the screen into a bitmap and replaces it upside down and backwards. So you can activate this on someone's computer and then the mark will sit down, look at the screen, and see that the computer is now upside down and backwards. (One click breaks the "spell," unfortunately, but hey, it's funny for a second.)
- cokegift: Many people have seen this one. When you activate this one, a Coke logo comes on and calls you a valued customer and says that because you're just that cool you get a free beverage holder. When you click to get it, your CD-ROM tray slides out. (It's a cup holder . . . get it?)
- mona: Yes, I ruin the surprise here too (to prevent anyone who doesn't want to see nudity from seeing nudity). When you activate this program, there is a picture of the Mona Lisa with a caption imploring you to press "space." When you do, her shirt goes down and you catch a glimpse of her titties. It is really infantile but funny for some reason. (Get out of this one by pressing ESC or pushing control-alt-delete and closing that program.)
- porn: This is not REALLY porn. It is a program that, when activated, brings up a little window that says "to get free hot, nasty porno pics, click here" or something. When you try to click, the button moves. It is funny. There are lots like this (click to find the meaning of life, click to get your annual bonus, et cetera), but I think this one's silliest. It's fun to leave on someone's desk or something.
- slippery mouse: Activate this program and suddenly your mouse is uncontrollable! Almost. It seems "slippery"; it responds too much when you move it and it is difficult to click anything. Activate this on their computers and a little box at the bottom reads "slippery mouse." They must somehow click it, and then it maximizes with a large button that says "KILL ME!" They must then click THAT to get their mouse back to normal. ::evil grin::
- finger: This turns the mouse pointer into a hand pointer every few seconds; a hand pointer with its middle finger up! It flashes once in a while and your victim will end up watching the pointer to see if it really gave him a bird.
- Go to wasarrested.com (or one of its associates) and create a headline about your mark's being arrested for something really embarrassing. Then send them the link in e-mail acting shocked and surprised at what they did. . . .
- You can also leave screen mates on the screen and see what people do. Pick from Screen Mate Poo (the sheep) or Screen Mate Mikan (the oranges). You can activate several of these guys and they'll run around, interact with the windows by sitting on them or falling off them, and sometimes interacting with each other or, in the case of the sheep, peeingon things or humping each other. FUN!!!
- Also, try Mega-Motivator (another suggestion by Jason V.): Install it on a friend's computer and then use its customizable message system to have it flash not hippy-dippy motivational messages but messages of paranoia, such as "They're watching you" and "They're in your head with their damn satellites." (Hey, great ideas, Jason!)
I'm sure you can come up with some mischief on your own. Lemme know if you want anything added to this list!
Thanks to Coolcan2 and Jason V. who contributed a couple of these pranks. :)