1/3 cup partially thawed frozen limeade concentrate
2 cups ice cubes
Using lime slices, moisten the rims of four margarita or cocktail glasses. Set aside lime slices for garnish. Sprinkle sugar on a plate; hold each glass upside down and dip rim into sugar. Set aside. Discard remaining sugar on plate.
In a blender, combine the remaining ingredients; cover and process until blended. Pour into prepared glasses. Garnish with reserved lime slices. Serve immediately.