I've noticed that. One day I went into a portajohn that is rarely used by men, but from which a hamplanet had just emerged. What do I see, a puddle of piss on the floor. At that moment I came to the (now obvious) conclusion that if you haven't seen your dick in so long you're not even sure it's still there, then you certainly can't aim, and probably most of the piss puddles on urinals are left by fats.