J.S.
I've dressed up as a cat and brought kitty litter cake to a party. It was hilarious! People thought it really was a real litter box. They were so grossed out when my husband ate some! The key is the tootsie roles made to look like poops.
http://allrecipes.com/recipe/kitty-litter-cake/
We always do a taco bar on Halloween for dinner. Great for the kids and easy for us. The kids expect it now.