Acultural

I am culturally clueless or, as I've said before, acultural. I used to think I was anti-cultural, but that's not really true since I do enjoy some cultural things. This morning, though, I was walking in to work and I saw a woman drive by. I could hear what I think was "gospel" music blaring from her car and she was driving with one hand.

She was moving her other hand, which was palm to the roof of her car with her fingers pointed behind her, up and down in a rhythmic fashion. I usually see this done with two-hands, but since she was driving, I'm glad she had at least one hand on the wheel.

So, what makes me acultural here is that I have absolutely no idea why people raise their hands above their heads in this fashion when listening to music or when they get particularly excited. People sometimes make a hooting noise to accompany the hand motions.

So ... why do people do this?! What is the significance? Does it represent something? How does one learn this behavior? I just don't get it ...