Office Pranks
Creamed

Shaving cream explosion.
Step 1: Freeze a can of shaving cream overnight.

Step 2: Remove bottom of the can of shaving cream while it's still frozen.

Step 3: Place the can of shaving cream in your coworker's desk when they aren't looking.

Result: The shaving cream will expand significantly inside the drawer. If you want to be nice, you can take out all of your victim's valuables from the drawer before you put the shaving cream in.
Photo by: ajay_suresh