Preheat your oven to whatever temperature your cake mix box specifies, usually 350°F (175°C). Grease your 9x13 inch baking pan well.

In a large mixing bowl, combine the white cake mix, 1 cup of water, 1/3 cup of vegetable oil, and 3 eggs. Mix until smooth and lump-free.

Pour the batter into the greased pan and bake for 28 to 32 minutes.

Once the cake comes out of the oven, let it cool for at least 30 minutes.

Use the handle of a wooden spoon to poke holes in the cooled cake, spacing them about 1 inch apart.

In separate bowls, dissolve each jello flavor in boiling water, then add cold water, stirring until dissolved.

Slowly pour the red jello into one half of the holes and the blue jello into the other half.

Cover the cake tightly with plastic wrap and refrigerate for at least 2 hours.

In a medium bowl, combine the thawed whipped topping with powdered sugar and mix until smooth.

Spread the whipped topping over the cake and sprinkle with colorful sprinkles.