2. Prepare the yellow cake mix as directed using a greased 13x9x2-inch pan and bake for 30-35 minutes.
3. While the cake is baking, combine the pineapple and 1 cup sugar in a saucepan and bring it to a boil over medium heat, stirring constantly. Remove from the heat and allow it to cool slightly. Remove the cake from the oven and, using a fork, pierce holes into the cake. Pour the pineapple mixture over the hot cake and set aside.
4. Prepare the pudding according to package directions. Spread the pudding over the cake and refrigerate until it is thoroughly chilled. Cover the top of the cake with Cool Whip and sprinkle the toasted coconut on top.