Preheat the oven to 350°F. Prepare a standard-sized bundt pan with baking spray, and set aside.

Mix the cake mix per the directions on the back of the box.

Divide the cake batter into 6 bowls. Color each bowl with a different food coloring, mixing well until the color is evenly distributed throughout and no streaks remain.

Starting with red, then orange, yellow, green, blue, then purple, add the colors to the bundt pan, and concentrate the next color in the center of the color you just placed. This will be a little time-consuming, do your best.

Bake for 40-45 minutes or until a toothpick inserted into the center comes out clean.

Let the cake cool in the pan for 10 minutes, then carefully invert the pan over a wire rack and let it cool completely.

Transfer the cake to a serving platter.

Place the tub of frosting with the top off and all of the foil wrapper discarded into the microwave. Microwave in 15-second intervals, stirring in between until the frosting is pourable.

Pour the frosting on top of the cake and let it drip down the sides; you may not use it all.

Immediately add sprinkles over the wet frosting so they stick to the icing. Let set up until the frosting has set.

Slice and enjoy.