To make individual drinks, fill champagne glass about 1/2 full with sherbet. Pour in orange juice to cover the sherbet, and then top with sparkling water. Serve with a straw for stirring.
To make as a punch, add sherbet to a large punch bowl, and break it up a bit with a spoon. Pour orange juice in, and then slowly pour in sparkling water. Stir with serving ladle frequently as you serve.
To make this a cocktail, use brut champagne instead of sparkling water!