Install the Blue Screen of Death screen-saver on someone's computer.

 862

3  

Hide an alarm clock in someone's bedroom and set it for 3:00 a.m.

 824

0  

Fill someone's hair-dryer with baby powder.

 781

1  

Pull on a coworker is to press ctrl+print screen on their workstation, then paste it into Paint, save the pic, and set it as the desktop background. Move all of their icons to the trash. When they get back to their desk, clicking won't accomplish anything!

 1626

0  

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.

 1521

1