Full disclosure: I've been known to invoke the five-second rule myself. But even the most ardent believers would probably find their faith shaken if the dropped foodstuff happened to land in a pile of cow dung instead of a tidy tile floor. So the "findings" reported in this Chicago Tribune article don't exactly shatter my paradigms.
Basically, according to Clemson University food scientist Paul Dawson, dropped food is a lot like real estate: location, location, location. But not in the way you might think. He says the kitchen and bathroom floors are zero-second areas due to the presence of bacteria, but the sidewalk is relatively OK. Unless, I would add, it's a sidewalk used often by livestock.
What's your stance on the five-second rule: words to eat by, or a joke to take your mind off the nasty stuff clinging to that Rolo you just plucked off the floor?