I once made the mistake of making a (true but) snarky comment to a co-worker, whose boyfriend happened to be a hobby taxidermist. They decided to get me back by filling the glovebox of my car with dead squirrels (which they conveniently had in their freezer, waiting to be stuffed).

They then arranged for a local cop to pull me over, and ask for my license and registration. I opened the glovebox to dig out the registration, and a seemingly endless cascade of dead squirrels began, while I started mumbling frantically....

My favorite low-cost easy-peasy make-'em-feel-stupid prank: take a screen capture of their desktop (without any windows open) and set the screen cap as the desktop background. Next, delete/hide (depending how nasty you want to go) all their desktop icons. If the taskbar is always visible, hide it too, or even better, resize it to zero pixels.

Step away from computer and find a nice vantage point to watch them click and scream at their non-responding computer.

Works a treat.

A friend of mine used to have a screenshot of winamp as his desktop. No matter how many times I used that computer to play music I'd always start by clicking on the fake winamp :p

I pulled that on several CS majors back in my college days. Works every time.

Air Conditioning ducts, particularly of those with Central Air.

Get some catfish bait, a few pounds of shrimp, fart bombs, or even a few dead squirrels - all of these worked well for me in High School.

Squirrels are probably by far the best and I recommend combining them with another form of attack. Place a few pounds of shrimp in one location and throw some frozen squirrels elsewhere.

About the time the shrimp smell really gets bad (about 2 days) the squirrels will be thawed and start to rot themselves. You'll get a nice delayed attack about a week after they find the shrimp.

yuck!

One of my colleagues was recently welcomed back fromholiday with this addition to his cron file:

0,20,40 * * * * /usr/bin/killall -9 java

Or is that going too far?

You automatically get rid of their memory leaks every 20 minutes. That's a service, not a prank.

Heck, I should add that to mine.

If they use a Windows computer, type the command Ctrl+Alt+DownArrow. It turns their screen upside-down. The other arrows work as well to turn the screen sideways. Not sure how familiar most people are with this though. I've always wanted to try it on someone and see how they reacted.

I'm so tempted to try it out with n number of windows m/c around ;)

That's an intel video chipset utility. More recent ones support Ctl-Alt(left|right) as well.

I cannot wait to use this.

It works under X as well.

$ xrandr -o inverted

To get back to normal,

$ xrandr -o normal

ahhh ... no it doesn't. perhaps with a third party monitor utility ...

It might be a Dell thing. I've only tried it on Dells and I've seen it work on a couple laptops and an older desktop. Haven't really tested this extensively though. YMMV.

A fellow sysadmin that I used to work with did a brilliant job of pranking me by quietly changing my ksh ENV variable to another file, and then aliasing a handful of commands (like su) to some brilliant ascii art taunts. As an added bonus, if I didn't clean the mess up in a specific order, then it attempted to repair any missing bits of itself.

I didn't know about the ENV variable at the time, so it took me a few minutes to puzzle out. I cheated with a carefully crafted find command.

We used Mac workstations in that office. The Mac OS has a sort-of vulnerability where, if you can get admin access to it, you can create an invisible administrator account on the machine with ssh privileges. I always wanted to do that, and then modify the su command on our server to watch for his username, ssh back to his machine, and play the "Oh my god, they gave you ROOT?!" clip from Jeffrey Hitchins' "Tech Support".

Back in my frat-boy college days, the best prank ever happened to me.

We were having a serious prank war. Then we had a dance marathon, which effectively left my room unguarded for 24 hours.

So the prankster removed all of my furniture, removed my carpet, and put my furniture back exactly where it was.

http://i28.tinypic.com/2ec17w1.jpg

So me and my friend come back, exhausted, and walk in to no carpet. We were too tired to be pissed.

He's now working for State Farm. Soon I will save up some money to rent a billboard in Tallahassee to make fun of him.

Soon, the day will be mine.

There's a variation of this prank which requires the victim to be drunk - and a fortuitous arrangement of rooms.

A student returned to his fourth storey room in a very drunk state and fell into a comatose sleep. While he was asleep, his friends swapped the contents of his room with an identical room on the ground floor. In the morning, four people with balaclavas burst into "his" room and threw him out of the window. Of course, he thought that he was on the fourth storey and that he was going to be thrown from a great height.

I heard of a guy who modified his friend's .bashrc to contain a sleep command with a variable time limit. Every time the .bashrc got run, the sleep command would run for a second longer. The first couple of times it was unnoticeable and after a few weeks he would log in, then go grab a sandwich before he could do anything. Subversive!

My buddy switched someone's explorer.exe with a Mac OS 7 emulator.

It was hilarious.

I once read a children's book about a company - actually a startup - that was in the service business of pranks and revenges.

You can find it on Amazon (http://www.amazon.de/Die-B%C3%A4rendienst-GmbH-Martin-Karau/...) - but it is in German.

Pranks are always tough, these aren't getting vindictive are they? If they are out to have fun, try photoshopping him into riske photos, tape/superglue his cubicle/something down, prank call him (impersonate some offical)...do something that gets his blood running that isn't permanent.

change their keyboard setting to dvorak. make sure they don't have to type a passwd. it's more funny to watch them type gibberish and know it.

route their favorite webmail client to a gay porn site (or straight, if they are gay..) through their hosts file

Icing sugar / flour, pour into the air intake ducts of their car. (Pro Tip: They are generally at the front, just underneath the windscreen.

It's easy... you break into the victim's flat, and wait just behind the door with a machete.

When the victim comes into their flat, slash violently at their neck area, several times if necessary. Make sure you're wearing cheap clothes that you're willing to burn, and have a change in a plastic bag in the bushes nearby, as well as a number of towels.

In my experience, this always stops prank wars quickly, effectively, and at a relatively low cost.

What!? Honestly, it's worked every time for me!

Your mistake was not including the fashion tip "Wear a Guy Fawkes mask".

Come one, no one sees the humor in this?

Geez tough crowd.

I'm surprised as well. Usually when I see things downmodded this severely I can at least see why.

Once downmods for a post cross a threshold, sheeps seem to get clicky.