Clowns use painted eggs to copyright their unique face paint.

When clowns join Clowns International in England, which claims to be the oldest clown society in the world, they register their individual make-up patterns in the "Egg Gallery". Eggshells are decorated as replicas of the clown's heads, and act as sort of clown copyright for the make-up designs.
http://en.wikipedia.org/wiki/Clown#Egg_Register

http://www.flickr.com/photos/lukestephenson/sets/72157606703952187/