Two glass houses/rooms would be setup for a few days in a high-traffic downtown location. The houses/rooms would be absolutely identical to each other. The two guys that would inhabit these places would be identical, and would do the exact same things (play video games, eat crap food, etc).

The only differences would be the clothes that each guy wears, and the clothes scattered around their rooms. In one, all the clothes would be clean, and the Purex Complete 3-in-1 Laundry Sheets would be heavily featured. In the other, all of the clothes are dirty.