Which number replaces the qu...

Two elderly gentlemen, who had been without sex for several years, decided they needed to visit a cat-house for some tail..... When they arrived, the madam took one look at them and decided she wasn't going to waste any of her girls on these two old men.
So she used "blow-up" dolls instead. She put the dolls in each man's room and left them to their business. After the two men were finished, they started walking home and began to talking. The first man said, "I think the girl I had was dead. She never moved, talked or even groaned... how was it for you?"
The second man replied, "I think mine was a witch. When I nibbled on her breast..... she farted and flew out the window!"