1. Set out 4 tall glasses. Add 1 1/2 cups of lemonade to a blender with 3 cups of ice. For green, add 3 drops of neon green and 2 drops of regular green. Blend until slushy, and divide evenly between the 4 glasses. 
2. Wash out the blender. Repeat the process with another 1 1/2 cups of lemonade and 3 cups of ice. For blue, use 3 drops of neon blue and 2 drops of regular blue. Carefully spoon the blue slush over the green slush. 
3. Wash out the blender again. Repeat with remaining 1 1/2 cups of lemonade and 3 cups of ice. For purple, use 3 drops of neon purple and 1 drop of regular blue. Carefully spoon the purple slush over the blue slush. Serve immediately with a decorative straw.

Calories: 81, Fat: 0 g (0 g Saturated Fat), Cholesterol: 0 mg, Sodium: 10 mg, Carbohydrates: 20 g, Fiber: 0 g, Protein: 0 g.