Place a few tablespoons of vanilla frosting in four small bowls. Use food coloring to tint one light blue, one dark blue, and one yellow. Leave the remaining bowl white. Transfer the frosting to separate ziplock bags and snip a corner from each. Frost, then pipe a letter onto each cupcake. Arrange them on a platter. Cut eight 1 1/2-inch and sixteen 2-inch lengths of red licorice twist. Using a knife make a slit in the side of each cupcake, then slide the licorice in place, using the shorter pieces to connect the small and large cupcakes.