That's not an ashtray you asshole.
There was this group of people in high school who would ash on the side of their shoe. They would cross their legs so that one shoe would be up in the air and the part of their shoe where the arch is would form sort of a makeshift ashtray. They would do this to feign consideration for whosever house they were in. However the true nature of this would present itself when it was time to leave at which time they would just stand up dumping all of the ashes and cigarette butts on the floor. I have seen this many times and I am fascinated by details and implications of it.