I'm sure I'm not the first person to get this idea, it's so simple and delicious. And low-calorie, too. And you can vary the recipe to suit your taste. You'll need a hand-blender or a hand mixer for this.
Pour six ounces of Diet Coke into a twelve ounce glass.
Add 1.5 tablespoons of sour cream.
Blend and drink.
You should start the blender at a slow speed, so that the soda does not avalanche out of the glass. You may wish to speed the blender up when the soda is under control. Very satisfying, for about 45 calories.