Preheat oven to 350 and spray a 9x13 pan with nonstick spray
In a large bowl, combine cake mix, eggs, mayo and 1/2 can pineapple with some juice
1 box yellow cake mix, 3 eggs, 1 cup mayo, 1/2 20 oz can of crushed pineapple
Using a hand mixer, beat cake mix well and pour into prepared baking pan
Bake for 30 minutes, or until toothpick inserted into center of cake comes out clean.
Allow to cool completely on a wire rack and then refrigerate
In a medium sized bowl, fold together Cool Whip, vanilla pudding mix, oranges and remaining pineapple with juice.
1 8 oz container Cool Whip, 1 box Instant Vanilla Pudding Mix, 1 cup mandarin oranges, 1/2 20 oz can of crushed pineapple
Cover and Refrigerate frosting until ready to frost and/or serve
Spread frosting over cooled cake and decorate top with more mandarin oranges