You drop a tasty cookie on the floor. Shouting, "Five seconds!" you frantically pick it up, blow on it and pop it in your mouth –- with the notion that if something touches the floor for less than five seconds, it's still clean and safe to eat. Noted food scientist Harold McGee, author of On Food and Cooking: The Science and Lore of the Kitchen and The Curious Cook: More Kitchen Science and Lore, tested the "five second" rule and wrote about his findings in the New York Times. Want to discover more kitchen science? Check out Harold's website.