Slap that puss!

I don't know if you're aware--maybe you are not the porn-watching kind (Why? It's delightful!)--but in porn, there's something that I think looks very odd. Okay, so the girl's rubbing her clit like mad, and then she occasionally just gives it a quick slap or two. Now, being a possessor of the almighty vagina, I understand that this might look a little weird, but the occasional tap on the clit feels really good. But since when has reality gotten in the way of a pornographer's vision? It looks ridiculous! I'd show you a clip, but I think I would violate a large number of laws regarding copyright and pornography (disseminating it to minors at the very least), but I imagine anyone with a sans-safety Google or an XTube bookmark could find what I'm talking about.
All I can think while goggling this kind of porn is that this girl is getting very frustrated at her vagina not working, and like any fickle mechanism, has decided to give it a quick few whacks in hopes that it will spring whirring into a frenzy of orgasmic convulsions--much like how I imagine my MacBook would work in a perfect world.