saw this YEARS ago and i've never forgotten it. photo of a woman who (from what you could see of her face) was quite attractive. half of her face was normal but the other half was completely covered with disgusting gunk. across the bottom of the poster was written "if what happens on your inside happened on your outside, would you still smoke?"
note: i've never been a smoker - i don't claim any virtue for this; it's just not anything i ever wanted to try. any sixers out there who are working on quitting or who want to, you have my very best wishes for your success!