human curiosity

Why is it when a bird poos on you, people like to say it's good luck? I mean, I get the idea that it's unlikely, it's supposed to make you feel better or something, like you are a chosen one. But, it's hollow isn't it? Isn't everyone aware that you were just shat on, and no-one ever feels lucky from that? Who are we trying to fool? Being shat on is inherently unlucky, and there's pretty much nothing you can say about it to convince me otherwise.