The logic of hand-washing

[squeek12]

I'm anticipating a flaming, but hear me out. What exactly is the logic behind washing your hands after pissing? I don't normally piss on my hands, but if I did, I would certainly wash up. On the other hand, on a clean trip to the head, I feel that if anything is leaving that bathroom dirtier than it was before, it's my schlong.

Consider the fact that your hands are the part of your body that most frequently come into contact with potentially harmful substances, and your penis remains safely tucked away in clean underwear. These two facts lead to the logical conclusion that you should wash your hands before you unzip, not the other way around.

I suppose it's just common courtesy, but if everyone thought logically, the hand washing custom would cease to exist? Am I out of line here?