Heat oven to 350 degrees Farenheit.

Make 8 ounces (1/2 box) of red velvet cake batter according to box directions, adding 1/2 cup sour cream before mixing. Be sure to use HALF of the ingredient amounts called for on the box! Set bowl aside.

Make white cake batter according to directions on box, adding 1/2 cup sour cream before mixing. Split cake batter into two equal amounts, adding blue food coloring to one portions until a bright blue color is achieved.

Coat three, 9-inch cake pans with cooking spray and lightly flour the bottoms. Add the three batters to the pans and bake at 350 degrees for 18-23 minutes, or until toothpick inserted into center of cake comes out with a few crumbs.

Allow cakes to cool in pans on wire racks, then turn out from pans onto a cutting board.

Using a 1.5 inch round cookie cutter, cut circles from each of the baked cakes. (You should get about 8 circles from each cake.

Using a jumbo sized straw or an apple corer, remove the center from each of the cake circles. Be sure to save the centers from the red and blue cupcakes, as you'll need them to plug the bottom of the blue cupcakes and the top of the red cupcakes after filling them.

Pipe a line of frosting around the top edge of the red and white cake circles. Stack the white cakes on top of the blue cakes and the red cakes on top of the white cakes.

Add Pop Rocks down the hollow centers of the stacked cakes. Put a portion of the red cake plugs back into the tops, covering the center filled with Pop Rocks.

Use kitchen to cut licorice rope pieces approximately 1-1/2 inches long and insert them into the centers of the red cakes.