I've been told before, when I mentioned I was Irish, that I must be "Black Irish." I nodded in agreement, not knowing exactly what that meant. But according to The Straight Dope, it must be true: "People talk about the Black Irish as though they constituted a mythical race on a par with the lost tribes of Israel. But in fact all they mean (usually) is that somebody named McNulty has dark, and in the classic case black, hair." I prefer the former definition, though.