I believe BB is right.  I was distracted by the 'Dynamic Knickers' comment.  The top of the buttocks shown should be smoother due to the muscles being pulled from that posture.

I cannot save the world. Only my little piece of it. If we all act together, we can save the world.--Nelson Mandela
An  inconsistent hobgoblin is the fool of little minds
Taking "Just do it" to a whole new level!