Take a square sponge cake.
Colour some of the icing blue, roll out thinly and cover cake with it.
Colour some icing black, and shape into a guitar, and some brown for neck of guitar.
Make some little oval shapes for pick ups and lay dental floss along for strings.
Shape some black icing into music notes, and some red into number 16.
Remove dental floss before eating, of course!!!!