Put tape over the optical sensor of someone's mouse.
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.
Find a sleeping person, fill their hand with shaving cream and then tickle their nose.
Hide all of the desktop icons on someone's computer and replace the monitor's wallpaper with a screen-shot of their desktop.
Install the Blue Screen of Death screen-saver on someone's computer.
Paint a bar of soap completely with clear nail polish so it won't suds up.
Hide an alarm clock in someone's bedroom and set it for 3:00 a.m.
Place a pair of pants and shoes inside the only toilet stall in a rest room to make it appear someone is using it all day.
Fill someone's hair-dryer with baby powder.
Remove the shower head and place a chicken bouillon cube in it, then put the head back on.
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