Step one: lie supine. Step two: twist the torso. Step three: make sexy face.
Here's Rihanna in the November 2012 issue of "Vogue."
Via: vogue.com
Look a little similar to the April 2011 issue of "Vogue"?
Via: models.com
And in other various photos.
Source: http://25.media.tumblr.com/tumblr_m8x3k6Uris1re77tfo1_1280.jpg
GQ, January 2011
Source: thisisthedream.com