Chocolate milk is (almost) always good. But in practice, it is mostly the little 250 ml snack drinks from the corner Korean store, such as Banana, or Strawberry, or Lychee/Peach (which is a bit odd at first, but surprisingly tasty.)
The Japanese / Korean Green Plum drinks can also be quite refreshing. And I buy 24-packs of snack soy milk or snack black bean drink.
I can't keep Chocolate Soy Milk in the house; I go through a 1.5 litre container of that in about 2 hours.
No coffee for me, though; it tastes bad to me even in fairly low concentrations.