"Brush with Greatness" is the eighteenth episode of The Simpsons' second season. In the episode, Marge revives her high school-era interest in painting by enrolling in an art class. Ringo Starr made a guest appearance in the episode as himself. He was the first Beatle to appear on the show.
"Homer's Barbershop Quartet" is the first episode of The Simpsons' fifth season. It features the Be Sharps, a barbershop quartet founded by Homer Simpson. The band's story roughly parallels that of The Beatles. George Harrison and David Crosby appear in the episode providing the voice for their own characters.
"Lisa the Vegetarian" is the fifth episode in the seventh season of the American animated television series The Simpsons. In the episode, Lisa decides to stop eating meat after bonding with a lamb at a petting zoo. Her schoolmates and family members ridicule her for her beliefs, but with the help of Apu and Paul and Linda McCartney, she commits to vegetarianism. Paul and Linda's voices are played by the real Paul McCartney and his wife.