The 1998 Banjo-Kazooie holiday card features a meatball-looking cake, this is actually a British dessert called plum pudding. The bottle Mumbo has says "Fust Plonk" which is aged cheap wine. The chaos on this card might indicate that Mumbo is inebriated.

Source: https://www.youtube.com/watch?v=n2zY6LC15Bs