Nakid. In this case the pic is a tease, the intent is to titillate men, it is not to say something that is true. This type of message is often used to draw attention so that an attempt can be made to sell something.
The word buff originally meant ‘a buffalo or other type of wild ox’, and buff leather, often shortened to simply buff, was leather made from the hide of such an animal. This leather was very strong, with a pale yellowish-beige colour. It was used to make military uniforms, and so soldiers would be described as ‘wearing buff’ or ‘in buff’. The combination of these descriptions and the similarity of the leather's colour to that of a white person's skin led to in the buff, ‘naked’. The buff meaning ‘the bare skin’ dates from the mid 17th century.