Alexander Burke writes: "The Annals of Improbable Research has a sidesplitting account of their research into exactly what the USPS will tolerate. They mailed various items -- ranging from the absurd to the grotesque, usually without packaging -- to various real domestic addresses. Said items include a hammer, a rose, a ski (!), a tooth, a brick, a helium balloon, a bottle of water, and many more. It's pure craziness, and definitely worth a read!"