Can you think of a memorable public-service advertisement from the radio? They are rare, but here is one that is both funny and effective. (The link is to a Windows Media Audio file. You’ll need to download it and then play using Windows Media Player, Winamp, or something else that plays WMA files. Go ahead. It’s worthwhile.)
As an exercise in rhetoric (persuasion through language), this ad uses two techniques that go back thousands of years:
(1) Instead of having a spokesperson earnestly tell you not to litter, it makes the point through a story, a modern parable with sound effects.
(2) The core argument is based on reciprocity—in this case, a twist on “Do to others as you would have others do to you.”
Mix these ingredients with fast-paced, clever execution, and you’ve got something that works.