The gals in my tech class do this quite frequently for each other's birthdays and they 'theme' them to whatever I happen to be teaching at the time. Utterly hilarious the things that people can come up with. We had the kitty litter cake during lab practicals with humane society animals, as well as a big round cake frosted like a red blood cell during hematology, a rectangle frosted light blue like a microscope slide with various jelly bean eggs and gummi worms for parisitology, and one frosted black with a glow in the dark halloween skelton on it for radiology. I do not recommend eating anything with black icing on it if you plan on smiling for the next three days...*g*
~J