Change the coffee in the office coffee maker to decaf.
1521
1
Write a message on an upside-down paper cup that alludes to something horrible being trapped under it.
Leave it on a coworker's desk or in a conference room.
1550
1
Install the Blue Screen of Death screen-saver on someone's computer.
883
3
Put a "Please Use Other Door" sign on the entrance to your office building if it only has one entrance.
1549
1
Hide all of the desktop icons on someone's computer and replace the monitor's wallpaper with a screen-shot of their desktop.
