I bumped into this via an article on Salon:
This bugs me more than meat-clown. I don't exactly know why; maybe it's the grinnin' pig sellin' porkflesh. Yeah, that's probably it. There are even bad cartoons touting the wonders of pork. I mean, it's low fat, right? That's why there's that folk saying, "thin as a pig," right? It's like a joke from old Simpsons, really, but it'd have Tress MacNeille doing the voices.