Well. I generally don't mention it unless there's a spesific reason to do so, OTOH hand I *assume* the non-American non-Jewish characters *have* one and so if it comes up, or it seems like something that scene/character would think about, I do.

I must also say, however, that I really, really dislike the whole ew, dirty, dirty foreskins thing. That's a crappy message to give anyone about their genitals and no better than 'ew! smelly cooch!'