Prepare cake mixes according to package directions. Grease 4 cake pans. Bake according to box directions.
When cakes are cooling, place 3 cans of frosting in a mixing bowl and add 2 tsp peppermint extract. Whip frosting till it's nice and fluffy. You can add a couple drops of red food coloring to make the frosting pink. Frost all layers and pour crushed peppermint on top and all around.