The ending to the joke told throughout the episode ("How do you think I rang the doorbell?") belongs to this:
A woman, tired of living alone, decides to put an ad in the local paper. She asks for three things: 1. A man who will treat her nicely, 2. A man who won't leave her, and 3. A man who is good in bed. Several weeks go buy without a result, and the woman is resigned to life without a man who can embody those qualities. Then, the doorbell rings and she opens it to find an armless, legless man in a wheelchair. He says, "I'm here about the ad in the paper. As you can see, I have no arms, so I can't beat you, and I have no legs, so I can't run away from you." The woman is skeptical, and asks, "Yeah, but are you good in bed?" The man answers, "How do you think I rang the doorbell?"