Watermelon Margaritas

Because of the sweetness of watermelon, this margarita doesn't require a lot of sugar, so it only has 105 calories in one glass. A little fresh lime juice gives the drink brightness and a pleasant piquancy. For extra flavor, sprinkle the glasses with powdered sugar and garnish with lime wedges and watermelon balls.
Pour 2 teaspoons of sugar into a saucer. Rub the edges of 6 glasses with 1 lime wedge; roll the edges of each glass in sugar to coat. Set the prepared glasses aside.Combine the watermelon and the following 4 ingredients (using Triple Sec) in a blender; whisk until smooth. Fill each prepared glass with 1/2 cup of crushed ice. Add 1/2 cup of "margarita" to each glass. Garnish with lime wedges or melon balls if desired.