Tisn't realistic in any event, since I can't get my hands on any hobbit, fat or thin, and it certainly didn't stop me from appreciating Mr. Astin's performace. It's just those big blue eyes...

Tom could be one of the big people, certainly, but if Sam's making up a song extemporarily you'd think it would be even more likely to be about familiar things, yes? Well, except for the Troll! Although maybe he was thinking of Tom Bombadil...