Same as if he said "this statement is a lie": his dick shrinks. Magic lamps, wishes on stars, and fairy godmothers all have a fault exception for trickery and judaism. That's why you can't wish for more wishes through lawyering. Your dick shrinks. Little known fact, the first circumcision was caused by Abraham trying to jew his way out of a magical contract... And he convinced a thousand generations that it's a normal thing to have, that everyone's dick should be like this, just so he wouldn't have to face the embarrassment in his lifetime.