[mmsc]

  こすり箸 Kosuribashi:
 To rub waribashi (disposable chopsticks) together to remove splinters.

I don't know about Japan, but everybody does this in Taiwan.

[Shank]

> I don't know about Japan

It is definitely not appropriate. If you break the chop sticks and use them correctly your fingers will never touch the surface where there are splinters.

[bitwank]

I always do it under the table; something I instinctively do without ever being told to. Now I wonder if I might have picked up on nonverbal cues at some point in the past. If I were someplace where chopsticks were the norm, I would probably just carry my own as I find the disposable wooden ones very off putting. I have to wonder if there is a rule about using your own chopsticks though.

[musicale]

Sandpaper and dremel aren't on the forbidden list yet.

[manarth]

I don't often bring sandpaper or dremel tools to a restaurant.

[xandrius]

Well, that's just against traditions.