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.

 462

1  

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

 502

3  

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

 492

0  

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

 551

0  

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

 429

1