Wait this is actually brilliant in a couple of ways, because to get the right (estimated) answer, the listener has to distinguish between probability that one of the three is a rabbi and this is a joke, and probability that this is a joke if we put the probability of the third being a rabbi at 100%.
It follows the setup of a rationality calibration question while subverting it and rendering "guessing the teacher's password" useless, since c) is (maybe) higher than a) or b)
Another month, another rationality quotes thread. The rules are: