I have to stand up in defense of the chopstick rubbing folks - I picked up this habit in China. I might have my issues with China, but mouth splinters are never a problem there because no one gets mad at you for rubbing your kauizi together. And to be fair, doing so shouldn't be offensive to the restaurant, but rather, to the chopstick manufacturer.

My dad immediately pours soy sauce over any bowl of rice presented to him, causing a massive faux pas in any Asian dining establishment. :) Wish I could break him of the habit, but alas, it's set for life. Then again, I guess I kind of appreciate the lack of pretense with which he regards his food. It's there for his enjoyment, not anyone else's sense of tradition. Call him a slob of an American if you will (he's Canadian) but at least he's free from worry and stress over things like soy sauce.