A working-class man who has been going steady with his upper class girlfriend for about a month is asked to have dinner with the girlfriends parents. They live in this huge mansion house in the country with servents and butlers etc, and everything is very very posh. Before dinner, he and his girlfriends parents are sitting in the drawing room, indulging in a bit of idle lighthearted hat before dinner, and everyone is laughing at his jokes and he is rather pleased with himself.
So, the time comes for dinner, and they are all sitting around this huge dinner table enjoying a 9-course banquet. But about two-thirds through the meal the guy has *really* got to fart. He asks to be excused to go to the bathroom, and asks for instructions on how to get there, and they give him a load of directions, and by the time he has spent around 5 minutes walking around corridors he is busting for a fart. He spots a window in the hallway he is in, and a split second thought crosses his mind. He runs over to the window, opens it, pokes his butt through the hole and lets out a massive earth rumbling wiffy fart. He closes the window and makes his way back to the dinner table rather pleased with his little idea (not to mention his farting prowess).
When he returns, the three others are eating in silence. He slips into his seat opposite his girlfriend, leans over and says "This is all going rather well, isn't it?"
Turning to him with a stern face his girlfriend uttered, "Everything was going fine, until you farted through the serving hatch!"