For those who have made the trip from New York’s JFK to Amsterdam’s Schiphol airport, you may have noticed a funny thing (well, at least the men may have noticed a funny thing): urinals in both terminals are marked by a little, off-center fly etched into the porcelain. It’s a transportative experience to fly across the ocean and see the same fly, perched in your pee receptacle. As if you could not outrun it. Upon closer examination, however, I realized that true to style, the Dutch fly was more intricate than its American counterpart, though the Dutch urinal was much smellier, due to it being a low-flow, non-flushing eco-toilet. Robert Krulwich has a theory about these flies, and why men instinctively aim for them.