My sisters birthday rolls around and last minute I decide to try this out.
I found a link if you need a how to...rainbows
What I did was, followed directions on the white cake mix box and added a sprite. Afterward, I separated the mix into four or five different bowls and added food coloring to each mix. Then you just pour each one into the cake pan as crazy or neatly as you want it. After its done baking use whipped topping to finish it off and VOILA..you have this...
Oh, and it tastes supaaaah awesome!