The fat guy seems to be mad that the guy he's facing is white more than anything. It's like he takes the guy's insults more personal because of it.
I've noticed that more and more white kids are rapping these days though. It's become sort of a college party trick. From New Orleans to NYC to ATL, I've seen it a lot in the 18-22 age group of America's white youth. At first, I thought it was just a New Orleans thing, but then going on this past road trip I realized that it's just become thing to do --- get fucked up at a party, someone plays a beat, and you start flowing... it's hard to perfect but easier to pick up than you'd think. I've heard some pretty ill flows from white dudes lately.