1Heat oven to 350°F. Place paper baking cup in each of 24 regular-size muffin cups. Make and bake cake mix as directed on box for cupcakes, using water, oil and eggs. Cool 10 minutes; remove from pans to cooling racks. Cool completely.
2Stir green food color into 1 container of the frosting. Stir purple food color into remaining container of frosting. Spoon each color frosting into separate decorating bags fitted with star tip. Pipe frosting on cupcakes to look like monster’s fur.
3Place 1 candy eye on each cupcake. With decorating gel, draw mouths. Insert 3 sour straw pieces into frosting on each cupcake to look like hair.