Switch the decaffeinated coffee with the caffeinated coffee. If they come in a can, pour the coffee out in a clean trash bag. Then empty the contents of the decaf into the regular can. Finish up by dumping the regular coffee from the trash bag into the decaf can.
Most people put so much sugar and cream in their decaf they will not be able to detect that extra buzz.
Advertise a colleague’s job and leave their number with extension for contact. Make sure it is well paying and with low qualifications.
Call one of your co-workers and tell them that you are a producer from the Ricki Lake Show and that someone from their past would like to confront them or reunite with them on the show. Then talk about airline reservations, hotel accommodations, etc. When they ask for more information, say that you're not able to give them any information and they will find out the day of the show. Their brains will be working overtime trying to think of who would want to confront them that nothing will get done that day.
(can substitue with jerry springer

Write a fake letter from some nameless union representative about a study that is being conducted on the effects of computer monitor radiation on men's sperm count asking them to bring a sample into work the next day. Ask them to drop off the samples with whomever you also want to embarrass. Then place copies of these letters in the pigeonholes of some men around the office you also want to get.
Paint a thin application of rubber cement on a railing leading down a flight of stairs.
Tie a thin monofiliment fishing line to the phone of your victim. Feel free to also attach other things such as pencil holders, lights, inboxes, anything easy and hopefully non-breakable.
Push the victims chair under the desk and tie the other line to a leg of the chair. When the victim pulls out the chair, everything goes flying off the desk on the other side.
Microsoft Word has a lovely feature called AutoCorrect. If you type in a word like "teh", it assumes that you really meant "the" and corrects the spelling of the word automatically.
You can view the entire list of words by going to Tools and AutoCorrect. The list is entirely editable and easy to change.
So what's stopping you from making a few changes?
Just head down the list and find a few easy to misspell words and have a little fun. A great one to start with is "the". Type in "the" and reword it to "teh"! But don't stop there. Type in "boobs" and make the correct spelling "knockers". Let your imagination run wild.
Just remember the words you set up so that you can easily change the list back at a future time.
Most people get frustrated and assume that Word is misbehaving. They never suspect it is a coworker that is defective.
This prank will really frustrate any hunt and peck typist.
Take a look at your keyboard. Notice how the M and the N key are just sitting there side by side? It's easy to confuse them. Especially if you swap around the keys on the keyboard.
Pry off the keys using a screwdriver or a house key. They should pop off rather easily. Swap the keys and press them back into place.
The great thing about this prank is that it can be done with just about any keyboard you run across.
Leave a message for a coworker that a "Mr. Bear" called for them. Write down the number for the local city zoo as the phone number to call.
Other useful names include: Buffy Lowe, Ellie Font, Jay Raffe, Ty Gere, Bab Heun and the old standby, Anna Conda
Take a container of lice powder and open it up. Leave the container in the bathroom when nobody is looking so it looks like someone just used it.
Take a piece of clear tape and place it over the mouseball. This will prevent the mouse ball from turning and frustrate the user.
This trick is quite easy for the user to figure out and it is easy to set up.
However, if you really want to be cruel, slightly unplug the mouse cable from the computer as well.
I copied and pasted it from a post someone made in a different BBS. ENJOY
BTW hitech be carefull if you are reading this. Because skuzzy probably already has.