Grease and flour twelve 2-1/2-inch muffin cups; set aside. Prepare cake mix according to package directions. Spoon half of the batter into prepared cups. Sprinkle each with 2 teaspoons chocolate pieces. Fill with remaining batter. Bake according to package. Cool on a rack.
Frost whole cupcake; roll in flaked coconut or sprinkle with toppings. (Save any remaining frosting for another use.) Chill at least 1 hour before serving. Cover; store in refrigerator. Makes 12 cupcakes.
If you like, line muffin cups with paper bake cups. Fill and bake as above. Frost only tops of cupcakes with frosting and sprinkle tops with coconut.