Well, we must admit people living in 17th century Holland had a sense of humor! : D
At first glance this image appears to be a simple picture of a smiling young girl, but it is in fact a prostitute’s portrait. Contemporary accounts record the display of painted likenesses of young women to advertise their availability. The medallion inscription, “Who can tell my backside from behind,” confirms the erotic nature of this image. The brilliant highlights that contrast against the dark background and the careful shading to create three-dimensionality were popular stylistic elements that the artist developed in Rome in the early 17th century. He has used them effectively to enhance the sitter’s physical presence.
P.S. The best-known woman's depiction from 17th-century Holland is Vermeer's Girl with a Pearl Earring. The identity of the young woman is still a mystery. Was she real? You can read about her here!