An Avon Lady was delivering products in a high-rise and was riding in the elevator. Suddenly, she had the powerful urge to fart. Since no one was in the elevator, she let it go - and it was a doozy.
Of course, the elevator then stopped at the next floor, so she quickly used some Avon Pine-Scented Spray to cover up the smell. Fergus entered the elevator and immediately made a face. "Holy cow! What's that smell?"
"I don't know, sir. I don't smell anything. What does it smell like to you?"
"Like someone crapped a Christmas tree."
(Originally heard at the Lympstone WI by my wife in 1984)