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Fill his/her clothing drawers with sand. If you have enough time, fill all of his/her socks with handfulls of sand. Liberally sprinkle sand in the underwear drawer, sock drawer, and all the other drawers. For extra fun, dip the socks filled with sand into water to soak the socks and ensure that the sand is much more difficult to remove. The finer the sand the better. It will take a great deal of work to clean all of it out. Sand is notoriously hard to remove from clothing.