5 tablespoons lemon-lime soda (such as 7-Up or Sprite)
In a cocktail shaker filled with ice, combine vodka, schnapps, lemonade and lemon-lime soda. Cover and shake vigorously. Dip rim edge of martini glasses in a shallow dish with 1/4-inch water, then in a shallow dish with 1/4-inch of equal parts sugar and cinnamon mixture. Strain shaken mixture into prepared glasses and serve.