Yes, but you are not in a joke on a train that has just entered scotland, are you, so the situation wouldn't have arisen, although, theoretically, if we actually live in infinite universes and the situation did arise within one of those, then you would likely have had your head in a maths book, merely overhearing the statements of the other two and so you could've easily said it out loud without the need to lift your head and observe said cow, thus removing the chance of ridicule because in your head the cow might not even exist.