Christians: Where do you draw the line on nudity?

Well, I think I'm a little more liberal than my mother in some respects. But I think it's a personal decision as far as the sexual nature of the nudity. However, I think it's also easier to watch--as a girl--nudity from my own gender. If I'm watching some movie where a girl walks around without a top, it doesn't really shock me or make me uncomfortable. Yet, I probably would have a problem if one of my brothers were watching it too. Just saying.