If you wear baseball caps (or know someone who does), they can become smelly and dirty rather quickly, especially if you make a habit of working out while wearing one. Washing a baseball cap is obviously greener than buying a new one, but how do you do it without ruining its shape? Your dishwasher, of course. Just place it inside your dishwasher sans detergent and run it on a regular cycle. After washing, stuff the inside with newspaper and let it air-dry. Good as new!