There was this one Old Farmer who was awakened late one night by a knocking on his door. The Old Farmer answered the door, and sure enough, there was the old cliche Travelling Salesman standing there. The Travelling Salesman said his car had broken down and asked if he could stay the night.
"Very well", the Old Farmer said, "But you'll hafta sleep with my Son."
The Travelling Salesman replied, "I'm sorry. I must be in the wrong joke."