Turns out MC Frontalot from Nerdcore, a band whose name pretty much says it all, decided to quit smoking the best way ever...by invoking D&D. From his blog post:
1. Name your character. Mine's Breathorr Inflatagon, a level 2 Lung Elf. You don't have to roll up stats. If you're a real stickler for form, go get your lungs x-rayed. The x-ray film is your character sheet.
2. Keep a d20 in your pack of cigarettes. If it doesn't fit, keep die, lighter, and pack together in some kind of totable container. May I suggest a pouch?
3. Whenever you feel like smoking, that means the GM (you) is trying to poison your character (also you). Time for a saving throw! I decided the DC (Difficulty Class) for my save vs Poison is 15. Roll the d20. 15 and up: I am saved from that cigarette I wanted! Hooray? 14 and under: oh darn, I get to enjoy another satisfying and flavorful cancer treat.
4. If you make the save, you really can't have a cigarette. Rolls have to be at least an hour apart. If you haven't rolled for two hours, that does not mean you get to roll twice. Be strict, or the GM Regulatory Cabal will revoke your authority. (I assume? I haven't GM'd since like 1988.)
5. Every day of the campaign, your Wisdom increases slightly. You're using Will to save against Poison, so increased Wis modifies in your favor (well, in your character's favor — your GM prefers that the poison attacks land). I'm using a mod of +1 for each day, so on day two rolls of 14 and up are successful saves, on day three it's 13 and up, etc. Fifteen days into the campaign, I will only be allowed to smoke when I roll a natural 1.
6. Rolling a natural 1, of course, is a critical fail. Thus, no matter how wise I get, I will always be able to sneak a cigarette if I can roll a 1. But after fifteen days I'm going to limit myself to one poisoning attempt per day, instead of one per waking hour. The game logic behind this is: fuck you, I do what I want.
Turns out, that he failed in his first attempt at this, and later amended his rules to include a "potion", also known as a piece of nicotine gum, every time he successfully avoided being poisoned. Seems to me like this little addition would be a vast improvement over the original.
The whole thing is pure genius, if you ask me.