Who's supposed to find this funny? I know I sure don't. It's like a stunt film to show that he's unbiased and willing to poke fun at the Left, or something. But if left-leaning people are supposed to feel chastened by it, I can't imagine any right-leaning viewers finding it even remotely humorous or forward-worthy.
It's like this is Rall's impression, as a Jane Goodall-like outsider, of what a right-winger might find funny, if only he could get into their thick heads.