Birthday cake "dip" made with 1 Box Betty Crocker Party Rainbow Chip Cake mix, 1 1/2 C. Plain Yogurt, 2 C. Cool Whip, & Sprinkles. Stir first two ingredients together in a large bowl until combined. Fold in Cool Whip. Chill for at least one hour. Cover dip with sprinkles before serving. Stores in the refrigerator for 3 days and can be frozen.