"Full Blast CD Trick"
You need:
A victim
A CD
Difficulty Rating: 1/10
This is a good simple trick to play in an office. You will probably only get to do it once on a person as after the joke they will most certainly check the sound setting before they turn their CD player online.
Find a CD that your victim likes but other people would be ashammed to own. When they leave their desk put the CD in their CD-Rom, then turn up the sound to full!
You will probably want to have the CD on auto-play.
Now your victim will be so embarrased because the whole office heard the awful music!