Prepare cake as directed in a 9"X13" pan, prepared with cooking spray. While still hot, punch cake full of holes, and drizzle the sweetened condensed milk over the top of cake. Spoon pineapple over the top next, and let the cake cool. Spread whipped topping on cake, and lastly, sprinkle top with the coconut.
Keeps well in the refrigerator if it lasts long enough to store.