Prepare cupcakes as directed on cake mix box. Sprinkle crushed graham crackers around edges, trying not to get any in the middle.
For frosting, mix about one cup of marshmallow fluff with prepared frosting in a medium bowl. More or less fluff, to your taste.
Allow cupcakes to fully cool. You can use either a pastry bag with a large tip, or a gallon zip bag for frosting. Fill bag with frosting. If using zip bag, cut about 1/4" off the corner. Pipe frosting onto center of cupcakes. Sprinkle with a light dusting of crushed graham crackers. Add 1/12 of Hershey bar for garnish.