1 box yellow cake mix, cook as directed & cool completely
16 oz. coconut, frozen or fresh
1 (16 oz.) sour cream
2 c. sugar

Combine last 3 ingredients and chill. Remove 1 cup of above mixture and set aside for topping. Slice cake into 3 layers and place filling between each layer. Mix remaining cup of mixture with 8 ounces of whipped topping and frost cake. Keep cake refrigerated in airtight container for 3 days before serving.