Bake cake according to directions on box, Cool and leave in a 9 x 13" pan. Spread on cake the 2 - 20 oz. cans of pineapple. Note: make sure the pineapple is well drained. Mix the 3 boxes of instant pudding with the 4 cups of milk. Spread the pudding on the cake over the pineapple. Spread the Cool Whip on next and then sprinkle coconut on top.