Anyone giving a polite or not-so-polite answer of “MYOB” or their favorite intrusive question in return will be automatically assumed to not have been jabbed, just because it’s the ones who have been jabbed who are the most eager to stick that fact in everyone’s faces, whether or not they were asked.
Indeed. The mere asking of the question tells them the answer, which is why it’s so important to discourage them from ever asking it again of anyone. An uncomfortably rude question in return might make all but the most oblivious think twice before asking it of a stranger again.
Kind of like when you could always tell a Trumper by the way they insufficiently denounced him when others were engaging in their daily two minutes Trump hate.