It takes place in the episode where Homer becomes a religious missionary to some island in order to escape paying PBS $5000. To teach them about religion he starts handing out Bibles. He is then told that they (the islanders) can't read. Later on Homer has a casino built for them. When Homer unvails the name of the casino, the same islander who informed him that they can't read reads out "The Lucky Savage" (the name). How can he read that, but not the Bible?