One person will add a fragment of the story, and another will build it up more, until we finally realize we're talking about something that is utterly imaginary and we stop and laugh.
Seems like attempting something like this would quickly unveil any programs that weren't truly artificial inteligence. In fact a true AI may not be able to fathom such a conversation.
Me and my friends AI-busting services can be had by and of you AI guys for a small but fair portion of any government grants you run across :)..j/k