1Heat oven to 350°F (325°F for dark or nonstick pans). Place paper baking cup in each of 24 regular-size muffin cups. To make red food color paint, in small bowl, mix 1 teaspoon water and 3 to 4 drops of the food color; set aside.
2In large bowl, beat cake mix, 1 cup water, the oil, eggs, cocoa and remaining food color from bottle with electric mixer on low speed 30 seconds, then on medium speed 2 minutes, scraping bowl occasionally. Divide batter evenly among muffin cups.
3Bake and cool completely as directed on box for cupcakes.
4Frost tops of cupcakes with frosting. Using a fine-tip brush, paint cupcakes with red food color paint, swirling paint to create design. Store loosely covered at room temperature.