Stir together first 3 ingredients in a large bowl, and pour mixture into freezer container of a 5-quart electric freezer. Freeze mixture according to manufacturer's instructions.
Pack electric freezer with additional ice and rock salt, and let sherbet stand 1 hour before serving. Scoop sherbet into bowls, and garnish, if desired.
Three-Ingredient Blackberry Sherbert: Substitute frozen blackberries for crushed pineapple and grape soft drink for orange soft drink.
Three-Ingredient Peach Sherbet: Substitute frozen peaches for crushed pineapple and peach soft drink for orange soft drink.
Three-Ingredient Strawberry Sherbet: Substitute 1 (16-ounce) package frozen sliced strawberries for crushed pineapple and strawberry soft drink for orange soft drink.