In a 16-ounce shaker, squeeze juice from the lemon and orange halves. Add sugar.
Add enough ice cubes to fill two-thirds full. Add water to cover ice.
Cover and shake. Serve in a tall glass. Garnish with orange wedges or lemon slices, if you like. Makes 1 serving.
For a lemon-only shakeup, substitute 1/2 of a lemon for the orange half.
