Flies and male psychology

Why is there a fly in the urinal?

Answer: To reduce spillage.

"So what do you think most men do? That's right, they aim at the fly when they urinate. They don't even think about it, and they don't need to read a user's manual; it's just an instinctive reaction. The interesting feature of these urinals is that they're deliberately designed to take advantage of this inherent human male tendency."

The fly in the urinal is a practice pioneered in Amsterdam's airport.

Talking about the science of urinals...