A travelling salesman fetches up one dark windy night at a remote farmhouse. He batters on the door, the farmers opens up and the salesman asks if he has a bed for the night. The farmer replies "Yes, but you have to share it with my 18-stone flatulent son?" The salesman says "I'm sorry? Don't you mean your 18-year old voluptuous daughter?" "No." says the farmer. "Oh, I'm terribly sorry," says the salesman, "I must be in the wrong joke!"