The first man stays with Joe and comes to breakfast the next morning with his hair a mess and his eyes bloodshot.
“What happened to you?” ask his friends.
“Joe snored so loudly I just sat up and watched him all night,” he moans.
The following evening, it is the second chap's turn. He also looks awful the next morning.
“Oh, man, that Joe shakes the roof,” he says. “I sat up and watched him all night too.”
The third night is Frank's turn, a burly ex-rugby player: a man's man. Next morning he comes down to breakfast looking very fresh.
“Good morning,” he says brightly.
The first two men are incredulous. “Wow, what happened?”
“Well,” says Frank.
“We got ready for bed, I tucked Joe in, wished him sweet dreams and kissed him on the forehead. He sat up and watched me all night.”