What a dilemma! I'm using the restroom at the Detroit airport during a layover. As I finish washing my hands, a guy comes from using the urinal and doesn't wash his hands, nearly running over me on his way out. A few seconds later, I emerge to see the same guy approaching some other guy he apparently knows, reaching out to shake his hand. Now, it occurs to me that I'd probably like to be told if I was about to shake some guy's hand after he's been touching his piece, so it's in my mind to scream out a warning, but what in the heck do you say in a situation like this? I mean, the guy probably has urine and heaven only knows what else splashed on that hand! Even sicker is the fact that it was lunch-time, and this guy probably went on to grab a bite to eat.