Thanks for the explanation. In retrospect, it seems obvious. But for me, when I heard “hockey mom,” that converted immediately to Sarah Palin. Then the joke became Sarah Palin vs. a pit bull, and incomprehensible.
Oh, I think that was the intent. If you were a lefty you were supposed to think "oh boy, he's going to zing Sarah Palin now!" and if you were on the right you were supposed to go "oh here they go again with the tired Sarah Palin abuse" then the surprise is he makes a crack about eating the dog. Whoa, didn't see that coming, wow, how funny! Hah hah hah. That's the way the script went. Trouble is, dog eating is one of the few issues left and right are pretty much in synch with, we all agree it's weird and unpleasant.
He was directing it at Sarah Palin. The comments he makes just before the hockey mom/pitbull joke referenced Palin on the today show.
Of course it was a play on Palin’s well-known line, given that she also described herself as a hockey mom—which is how it is also dig against her.
I don’t think it’s particularly funny, but it isn’t nonsensical.