Preheat oven to 350 degrees F.
In a large bowl, whisk together the cake mix, instant pudding mix, melted butter, eggs, and sprite.
Grease a mini bundt pan and fill each cake slot 3/4 full of batter. Cook for 18-22 minutes or until a toothpick/knife comes out of the center clean. For a full size bundt pan, cook 38-40 minutes.
Let cool for 10 minutes, before inverting onto a wired rack. Let cool completly before frosting.
Stir together the powdered sugar, lime juice, lemon juice, half and half, and zest from one lemon and one lime. Drizzle the tops of each bundt cake with the icing.