Grama's Coconut Pineapple Cake

1 yellow cake mix, baked
Let stand 5 minutes, then poke holes in cake with large fork.
1 pkg instant coconut pudding (make with 1 1/2 c milk)  Fold in 8 oz cool whip into pudding.  Top cake with 1 can of crushed pineapple, pudding mixture, and flaked coconut