When cake is cooled, combine 1/2 cup boiling water with blue jello in a bowl.
Stir until dissolved.
In another bowl, combine 1/2 cup boiling water with red jello.
Stir until dissolved.
Using a wooden spoon, poke several holes in the cake.
Carefully spoon jello mixtures into the holes, trying to only pour one color into each hole. Also be sure to spread the colors throughout to create a fun color pattern.
Place cake in the refrigerator for 30 minutes to allow jello to soak in.
Frost with whipped topping and garnish with sprinkles.