I'd like to preface that I play guitar for a living now and am well versed in what I believe are the greatest guitar players in history such as Chet Atkins, Tommy Emmanuel, Django Reinhardt, Joscho Stephan, Lenny Breau, Martin Taylor, Brent Mason and many, many more.
I think the part at 2:17 is well, juvenile. Just a bit of quick slapping while pulling the string up high like he's yanking a dick off. It's a bit like a slap bass. Just my opinion.
I don't think I could play it that fast right now, but it's really just typical slapping technique done quickly and violently.