A man walks into a bar, orders a pint of bitter and walks over to an empty table. He puts his pint down on the table and just as he's about to sit decides to go for a pee. "Excuse me mate," he says to the man at the next table, "would you mind keeping an eye on my pint while I nip to the loo?" "Of course not," replies the man at the next table. Our hero zips off to the loo. As soon as he's through the door, a woman sitting on the other side of the bar walks over to the unaccompanied pint, lifts her skirt, squats, breaks wind violently into the beer and returns to her seat.
The first man exits the loo, returns to his table, sits and makes to take his first sip of beer. "Excuse me mate," says the man who agreed to beer-watching duties, "I wouldn't touch that if I were you. That woman over there just broke wind very violently right into your beer." Our man sets down his pint and walks over to the woman. "Excuse me. You fart in ma Whitbread?" "No," she says, "I'm Tessa Sanderson."