Kenny’s joke shows that he’s still in good spirits and also emphasizes his abrasive, judgmental nature. Meanwhile, Tub and Frank’s squabble indicates a turning point in the men’s relationship. Tub’s emotionally charged response to being called a “fat moron,” foreshadows his later conversation with Frank, in which Tub reveals that he has a serious addiction to food and overeating. It’s also somewhat clear that now that Tub has shot Kenny and lashed out at Frank, he has more power than he had before; both Kenny and Frank must, to some extent, defer to Tub now.