Take 1/2 cup of your royal icing and dye it black using black food coloring. Once you reach your desired shade of black, thin to 15 second consistency. Add to piping bag and snip off a small tip.
Thin remaining white icing to 10 second consistency and add to a piping bag, snipping off a small tip.
Frost cookies with white icing allowing it to drip over the sides.
Immediately add cut marshmallow towards the back of the cookie Add M&Ms and then pipe black stick arms "floating" out away from the head while icing is still wet.
Allow the cookies to set for 20-30 minutes before decorating the face with two eyes, a surprised 'O' for a mouth. Use some leftover white icing to attach the orange sprinkle nose.