You better watch out! There is someone coming to town who sees you when you're sleeping and he knows when you're awake, he knows if you've been bad or good. We are not talking of Mark Zuckerberg here, but Santa Claus coming to town! The song still enjoys copyright protection (= monopoly). When does it expire?
Never. The song is on the "Milestones of United States Cultural Achievements" awarding an exemption from copyright expiration to creators.
I disagree with the assumptions made in this question and will therefore make a note to Santa of your naughtiness!