I'm flummoxed by those rap hand gestures. I found this from The Blue Brick, Hand Gestures Ruling Rap:

So what is it about a rapper�s contorted hands that draw us to them? Psychologist Timothy Ovitz has been studying the phenomenon. �The only thing that I can come up with to account for the power of these ridiculous gestures and posing is the astronomical drop in the intelligence of our youth�, offers Ovitz. His studies involve playing rap songs of very poor quality to a group of teenagers, and having them write down their opinion of the song. Then, the same song is played, but the image of a rapper displaying various hand gestures is shown during the song. Again, the teen� opinions are documented. The results are staggering, says Ovitz. �First, the subjects hate the song. Then, after seeing a rapper doing something as inane as curling their fingers, as if they were tightly gripping a grapefruit, and moving their hands and arms up and down, they suddenly love the damn (rap song)�.

Then there's this one.

I should not mention that in the same breath as hastas and mudras.