This could even be made "legal" using sugar free pudding. Don't know what you'd do about the frosting though.
2 C. milk I box vanilla pudding mix I z. tub thawed Cool Whip I box graham crackers I container chocolate frosting
In a medium bowl, mix the milk and pudding mix till mix dissolves. Fold in the Cool Whip. In an 8"x8" baking dish, place a layer of graham crackers on bottom (you may have to break up some to fit). Spoon a layer of the pudding mixture. Place another layer of crackers and pudding mix till you reach the top of dish, making sure the top layers is graham crackers. Top with the frosting. Chill in the fridge for about 4 hrs. and ENJOY!!!!!