Add vodka, OJ, and triple sec to an ice-filled shaker. Shake, strain, and pour into two glasses over new ice. Top with sparkling water/soda and garnish with orange slices.
You can substitute unflavored vodka in a pinch, or you can create your own orange-flavored vodka by taking two sliced Valencia oranges (or tangerines) and soaking them in 2 cups of vodka for at least a week. (You can leave the oranges in the vodka for even longer if you like, since they won't develop the bitterness that can come for soaking lemons or limes for too long.)