Make cake mix according to directions. Mix jello using half the amount of water called for and let cool slightly (do not let it firm up).
Take baked cake and using a prong or large fork poke holes all over top of cake. Pour jello over top of cake allowing it to run into cake and slightly over sides. Ice cake using the whipping topping and keep in refrigerator allowing jello to set up.
Slice and enjoy. Nice at christmas to use lime and strawberry jello.