If I'm ever posed that question I'll usually take a more hands on approach. If it's possible, I'll put something on and tell them to watch it and tell me what's wrong with it. Then I can counterpoint each argument as it comes up, cause I'm always better on the fly like that. I'll usually compare it to ballet, which will sometimes take someone off guard, cause most tend to downplay that similarity.
Oh, and don't be afraid of being a mark. Smarks are assholes.