The scourge of T-shirts for eons, sweat and antiperspirant come together to make an ideal waterproof mixture that cakes up and yellows white cotton. Weiss, however, has a few tricks up her sleeve. "Meat tenderizer is the best for perspiration stains," she says. "Meat tenderizer is a protein enzyme, so about 30 minutes after applying it to a stain, it should eat through it completely." The next best thing is crushed aspirin, which works in a pinch if you happen to be sans tenderizer for some odd reason. Take a few aspirin, pulverize them, and add just enough water to make a thick paste and apply it to the yellow areas. After it sits for several minutes, wash as usual. Repeat if necessary. Whatever method you choose, resist the urge to use bleach on white shirts: It turns out that move can actually make stains worse. Finally, Weiss offers a shortcut: "Wash your shirts inside out, which will help get traces of deodorant off."