Mickey's Good Deed (1932)

Mickey is playing Christmas carols on a standup bass for change. Alas, all he gets is screws, rocks, and other useless stuff. He plays outside a rich man's window, and the spoiled brat kid inside decides he wants Pluto. Mickey isn't selling, but when his bass gets destroyed by a passing sleigh and he sees a house full of orphans with no presents, he changes his mind. Mickey plays Santa to the kids. Meanwhile, the brat has been torturing Pluto; his father finally has enough and throws Pluto out and spanks the child. Pluto and Mickey are reunited, and as a bonus, the kid has tied the Christmas turkey to Pluto's tail.
(Also included: Chip an' Dale 1947, Lend a Paw 1941)