As used on the Simpsons episode "Lisa the Tree Hugger", animal/enviornmental rights activist, Jesse tells Lisa that he is a level 5 vegan, who wont eat anything that casts a shadow. Such thing doesn't exist, mind you.
Jesse: Heh. Well, that's a start.
Lisa: Uh, well, I was thinking of going vegan.
Jesse: I'm a level 5 vegan -- I won't eat anything that casts a shadow.