What is a polite, respectful way to tell a lady that she (G)

You might be able to tell them without saying anything by tapping to the part of the face after making eye contact... that's the quiet and more subtle way to go about it, especially if around many people.

People will probably feel a little embarrassed no matter how you address it, though, but it's so much more embarrassing for them to find out hours later about it by looking in the mirror... lol

Both suggestions I had were already mentioned. Just be discrete.

Yes, I agree. It does depend a little as to where you are, who she is and how well you know her.

Not really. You should be straight with everyone, regardless of gender. Yes, it's somewhat embarrassing, but it's something that can happen to anyone.

Just tell her straight up. Better to be honest than not.

One time in Middle School a long time ago (8th grade I think), I had a rip in my pants and no one told me. Made for an embarrassing day that could have been avoided if someone just told me, but no, they were either too scared or wanted a free show. I think I skipped school for two days after that.