Using the Mars Hand Lens Imager (MHLI) at the end of its arm to take dozens of images of itself (selfies). The images were taken in April and May (2014) while the rover was doing science at the Windjana drilling site.
Winjana is inside a science waypoint called “The Kimberley” and was chosen were sandstone layers with varying exposure to the Martian wind which causes erosion. A great spot for science samples.
What you don’t see in the image is the rover arm. What you can see are the holes drilled by by Curiosity’s drill out in front of the rover. You can spot them left of center and down a little, look for the gray spots. We can see dust accumulating on the rover, not too bad yet.
See this links to more images and details at the NASA site.