What is the muscle under your hip bone (remember the sexy D'angelo video?) called? Are there specific exercises that will help build this muscle? I searched online but couldn't find a good answer. Hope you all can help!
http://www.metroactive.com/papers/sfmetro/03.06.00/gifs/music2-0008.jpg
http://www.metroactive.com/papers/sfmetro/03.06.00/gifs/music2-0008.jpg