When I was a kid - like 5-6 years old - I ate the ashes out of an ashtray. I was curious of the wierd taste and the quasi numb feeling my tounge had after eating it, so I kept at it - until the ashtray was empty. My old baby-sitter used to smoke a ton of cigarettes, so this explains the abundance of charred tobacco.
I am happy to report that I have, since, stopped practicing this behavior.

