Prepare the cake in a 9 x 13 baking dish following the instructions on back of cake mix box. Cool cake for 10 minutes.
Using the end of a large utensil poke holes all over cake.
Make the pudding using the instructions on back of pudding package. Make sure pudding maintains a consistency that will easily pour into holes of cake.
Pour pudding all over cake aiming for the holes. Smooth pudding over holes of cake to fill. Spread evenly left over pudding to cover cake and down the sides.
Refrigerate cake for 1 hour to set the pudding.
Place bananas on the set pudding in single layer to cover entire cake.
Sprinkle 1/2 of the crushed vanilla wafers all over the bananas.
Dollop whipped topping all over the crushed wafers and smooth out evenly.
Sprinkle the remaining crushed vanilla wafers over the whipped topping.
Refrigerate until ready to serve or enjoy now.