 What isn't something the guest expects the younger man to do?
There is one fact no sane man can quarrel with ... But some men aren't sane; thus it isn't always so! You will, you know, so why quibble about it? At least, you always have ... or do ... or will. You're wondering whether to give me a drink, as I remember it. And naturally, since we have the same tastes, you can make the same for me as you're having. So let's begin when you get up in half an hour and come out with me. Yes, it'll be pretty obvious it must be a time machine. Then you feel silly, because you'll remember that I said you'd ask that.
 listen to his directions very carefully
 steal something from a museum  take credit for an invention from the future  run the time machine  listen to his directions very carefully