If you're in cubicle hell, this prank works great. The average cubicle size is 8x8. So first procure about 30 large bags of styrofoam packaging popcorn. You can usually get this from Office Depot or any packaging store for about 20-30 dollars. The bags should hold contain 12-13 cubic feet of popcorn. THe bottom line here is that you'll need 384 cubic feet of popcorn (8x8x6).

Saran wrap the opening to the person's cube so that you've completely sealed the cube. Simply use duct tape and tape the strips across the doorway. Then start pouring the foam in. If you don't want to create too much havoc, I'd suggest tossing the full bags in there, that way it's easier to clean up. The important thing is that the doorway and the top of the office make it look full.

This can be done in a few hours. Make sure to take pictures of the person's face when they finnaly see their office.