Nudity is a special case because of what it communicates. We can think of various ways that we use our bodies to communicate nonverbally. Consider the meaning of the hug, or the handshake, or the slap on the face. There must be a hundred messages we can send with our hands alone.
So then, what does it mean for someone to remove their clothes? To be blunt, removing the clothes exposes the genitalia, which is the most intimate part of our bodies. What idea does a woman express when she removes her clothes in front of a man? What is she saying with her body? What does her body communicate that her words, perhaps, do not?