if all else fails, appeal to vanity.

the New York Times had an article on the nasty oral effects of crystal meth:

Grisly Effect of One Drug: 'Meth Mouth' - New York Times

I have long been wondering why anti-meth ads didn't push this angle. Meth users have seriously N A S T Y breath that no amount of brushing or gum will cover up. The stuff will rot your teeth out faster than if you sucked on sugar cubes all day everyday. It destroys you gums and will rot a hole straight on up into your nasal cavity. And it doesn't waste time doing it. It pisses me off that the gay community isn't going apeshit about the dangers of meth right now, with its use on the rise and with its close association with unsafe sex pratices. But I have always thought that the easiest angle to tackle this from is the it-will-fuck-up-your-grill angle. Go with the immediate, go with the one that will make them ugly quick. Meth makes your breath smell nasty, and it will destroy your teeth. Say it everytime you hear the drug come up in conversation.