This Chick Had Her Dress Inside Out........?

You could have gone with something like "your tag is sticking out". That way, if she truly had no idea that it was inside out, she would have noticed at that point without the public embarment of being told that she was wearing her clothing inside out. It is much less embaring to be told that your tag is sticking out, most bystanders won't even bother to look. However, if someone mentions that you are wearing something inside out, then ususally you get some interest from the bystanders.