If we're talking about increasing gun safety through numbers reduction, the most effective words in the English language will be "Ewww," "So 2011," and "Jesus, what a pain in the ass."
Our discussion of which weapons and ammunition to ban (See "Black Rifle Blues") is fraught with inconsistencies and plagued by the reality that sometimes, making something illegal increases its appeal.
But MADD and the anti-tobacco folks understood that the perception of unfashionableness is among the world's most powerful forces, and used it to their advantage. It took a long time, but fewer people drive drunk now, and these days, you can go to a bar in quite a few places without coming home smelling like smoke. In the case of tobacco, this was accomplished by some lawsuits, a few bans, and a lot of encouraging people to see cigarettes as just not as cool as previously thought.