1 box Duncan Hines butter cake
1 (12 oz.) pkg. coconut
1 c. sugar
1 (16 oz.) carton sour cream
1 (9 oz.) carton Cool Whip

Bake cake in 2 round layer pans; allow to cool. Cut each layer in half to make 4 layers. Mix next 3 ingredients and chill. Save out 1 cup of sour cream mixture and add to a 9 ounce carton of Cool Whip. Spread coconut-sugar-sour cream mixture between cake layers. Ice cake with Cool Whip mixture. Can be baked the day before and refrigerated.