As all women who have ever shared a toilet with a man can attest, men can be especially spacey when it comes to their, er, aim. In the privacy of a home, that may be a mere annoyance. But, in a busy airport restroom used by throngs of travelers each day, the unpleasant effects of bad aim can add up rather quickly. Enter an ingenious economist who worked for Schiphol International Airport in Amsterdam. His idea was to etch an image of a black house fly onto the bowls of the airport’s urinals, just to the left of the drain. The result: Spillage declined 80 percent. It turns out that, if you give men a target, they can’t help but aim at it.