Remove the shower head and place a chicken bouillon cube in it, then put the head back on.
 642
1  

Find a sleeping person, fill their hand with shaving cream and then tickle their nose.
 744
0  

Fill someone's hair-dryer with baby powder.
 697
1  

Put a "Please Use Other Door" sign on the entrance to your office building if it only has one entrance.
 1377
1  

Hide all of the desktop icons on someone's computer and replace the monitor's wallpaper with a screen-shot of their desktop.
 811
0