A Tom and Jerry is a traditional Christmastime cocktail in the United States, sometimes attributed to British writer and professional boxing journalist Pierce Egan in the 1820s. It is a variant of eggnog with brandy and rum added and served hot, usually in a mug or a bowl.
Another method uses egg whites, beaten stiff, with the yolks and sugar folded back in, and optionally vanilla extract added. A few spoonfuls are added to a mug, then hot milk and rum are added, and it is topped with nutmeg. Pre-made Tom and Jerry batter, typically produced by manufacturers in Wisconsin, Minnesota and the Dakotas, is sold in regional supermarkets during the Christmas season.