Preheat oven to 350°F. Line muffin pan with baking cups
In large bowl, combine cake mix and cocoa.
Add eggs, water, and mayonnaise; beat with electric mixer on low speed 30 seconds, scraping bowl frequently.
Beat on medium speed 2 minutes. Pour batter into prepared pan.
Bake 18-20 minutes or until toothpick inserted in center comes out clean. Cool completely before decorating.
Makes 24 cupcakes.