To be fair, the Passover story is part of the JW kid's religion and culture as well, and I don't see why the Jewish girl has any better claim on it.
"Right. Go ahead Con. In front of all these people, you, the Jehovah's Witness, tell the Jewish girl all about how the Jewish holiday works."
It looks as if Con has been the victim of religious bigotry. Would it be acceptable to mock a Jew in the same way?
"In front of all these people, you, the Jew, tell the Jehovah Witness boy all about how the Jehovah Witness commemoration works."