Pre-heat your oven to 350° F, or whatever temperature it says on your specific cake mix box.
Mix together the cake mix, water, eggs, and canola oil.
Pour the cake batter into a greased 9x13 cake pan, and bake according to the package directions on your cake mix.
When the cake is fully baked, remove it from the oven, and allow it to cool for 15-20 minutes.
Meanwhile, mix half of the blue Jello mix (1.5 ounce) with 1/2 cup boiling water 'til the Jello mix dissolves. Then add 1/4 cup cold water, and mix well.
Then mix half of the red Jello mix (1.5 ounce) with 1/2 cup boiling water 'til the Jello mix dissolves. Add 1/4 cup cold water, and mix well.
Poke holes all over the top of the slightly cooled but still warm cake with a fork. I find that a fork works really well, but you can also use the handle of a wooden spoon or a wooden skewer if you want bigger holes.
Carefully and slowly pour the blue and red Jello mixture alternately over the entire cake. I skip around with the red Jello, and then I fill in the rest of the cake with the blue. A funnel pitcher works great for this.
Allow the cake to cool completely.
Then spread Cool Whip or whipped topping over the top of the entire cake.
Chill the cake for at least 4 hours, or better yet overnight, before serving.
Before serving, sprinkle 4th of July sprinkles all over the top of the cake, as many or as few as you want.* Then slice and serve the cake.