It looks exactly like a nude woman with a bottlecap hat, it has to do with the shading. The pic you posted looks like clay, the OP pic looks like shiny skin. Yeah it's not 100% photorealistic, obviously some details are missing, but the details that are there paint a picture. A nude picture, specifically, I'm pretty sure I can make out nipple and areola.

That detail + shading approximates nudity.