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.
 1569
1  

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.
 802
1  

I just recently discovered that there is a national holiday named after Atheism. April FOOLS day. Like this story in the name of Jesus.
 2072
0  

Hide all of the desktop icons on someone's computer and replace the monitor's wallpaper with a screen-shot of their desktop.
 973
0  

Change the coffee in the office coffee maker to decaf.
 1535
1