The implications of the joke's simple logic are enormous. Our picture of the cause & effect driven universe must be now adjusted. And that's a big headache to physicists. There are also psychological implications. People who believed that they were driven by external causes - tended to exercise their free will much less. They were also tending to be dishonest. Religious thought is also impacted. Previous believes that "everything is God's will", "everything is preordained" or "written" will have to be adjusted. Hopefully, "suicide missions" will also become a thing of the past. As you see, plenty is at stake here - including our own freedom. Please vote.