John is on a raft, adrift in the ocean with several other survivors of a shipwreck. The others are too weak, so he or Mike will swim to a nearby island to look for help. It is almost certainly suicidal, due to the circling sharks, but they have little else to hope for. Mike takes the lose change from his pocket and puts two pennies in a hat. He tells John that one is a 2005 penny, and the other 1975. If John picks the newer penny he can stay on the rat, and Mike will risk his life. If John picks the older penny, he must go. John has seen that both pennies were actually dated 1975, but he doesn't want to say anything, because Mike is a big guy. How does he win, and get Mike to go, without exposing him as a fraud in front of the others?