Bake chocolate cake in a 9x13 inch pan according to package directions and let cool for 10 minutes.
Use the handle of a wooden spoon to poke holes all over the surface of the warm cake, spacing them about an inch apart.
Whisk pudding mixes with milk for 2 minutes until slightly thickened, then pour immediately over the cake so it seeps into the holes.
Refrigerate for at least 1 hour until pudding is fully set.
Fold marshmallow fluff into whipped topping and spread evenly over the top of the cake.
Sprinkle with crushed graham crackers and mini chocolate chips before serving.