Preheat oven to 350F and line a 12-tin muffin tray with liners. Spray with cooking spray and set aside.
In a large bowl prepare cupcake batter according to box directions. Add 5 tablespoons batter into each cavity on prepared muffin tray (you might have a small amount of waste). Bake for about 15 minutes or until a toothpick comes out of the center of the cupcakes with moist crumbs. Set on a wire rack and cool slightly.
Poke 4 holes in each cupcake about ½ to 1cm (around ¼ inch or a little bigger) in diameter (I used a chopstick) about ¾ of the way into the cupcakes.
Prepare blue Jello in a small bowl or spouted measuring cup by adding 1.5-ounce Jello mixture (half of a small box), followed by ½ cup hot water. Stir until dissolved then add ¼ cup cold water.
In another bowl, repeat for the red Jello.
Carefully spoon Jello mixtures into alternating holes, pouring one color into each hole. Each cupcake will have two blue holes and two red holes.
Refrigerate cupcakes for 60 minutes to allow Jello to set.
Add Cool Whip on top when ready to serve. Finish things off with sprinkles and sparkles. Enjoy every bite.