1 pkg. butter flavor Duncan Hines cake mix
2 (8 oz.) cartons sour cream
2 (6 oz.) pkg. frozen coconut (semi-thawed)
2 c. sugar
9 oz. c. Cool Whip

Mix sugar, sour cream and coconut together. Let set overnight in refrigerator. Next day, bake cake and split layers. Reserve 1 cup of mixture; set aside. Divide remaining mixture generously between layers. Blend reserved 1 cup remaining mixture with Cool Whip and cover sides and top of cake. Refrigerate overnight.