What's with her lay back spin move?

Was flipping through the channels and this was on one of those Starz channels and it was the lap dance scene in the strip club. During the scene, when she starts to get real intense and ride him, she lays back and does this spinning motion with her upper body that looks awkward and not even enjoyable for the guy.

But then later on in the pool scene when they're having sex she busts out the same move and it looks even more awkward in that scene because it looks like she's being attacked, not having sex.

I wonder if that's like an Elizabeth Berkley go to move in her personal life, or if she just thinks that's something guys think is hot. It just adds to the awkward hilarity that is this movie.