Last Unsmoked Cigarette

A character who has quit smoking or drinking keeps one, last unsmoked cigarette, or one last bottle to remind him of why he quit. May be a dare, a test where he can prove to himself that he has quit for good, a quitting device to prevent him from buying more, or a memento to remind him of what they were like before quitting.

Sometimes, if the character goes through a particular level of stress, but particularly if he is doomed, he may light up that last cigarette or swig from that last bottle. Especially if he's making a Heroic Sacrifice.

May also be a Chehkov's Gun.

Film

 * 1408: Mike Enslin keeps a last, unsmoked cigarette to remind him of why he quit.
 * In the movie, The War of the Roses: Each spouse is trying to force the other out of the house while they are getting a divorce. Their (yes, they share one) divorce lawyer has a glass-framed last cigarette; he smashes it in while dealing with them.

Live Action Television

 * Murphy Brown: In the first episode (and through the first season) Murphy carried around one last cigarette.
 * Cheers: An episode focused on Sam's Lucky Bottle Cap. The cap from the last beer Sam drank before giving up drinking for good.

Literature

 * Discworld: Sam Vimes, who quit drinking a little while after meeting Sybil, keeps a drink in his desk drawer. Note that it's not good alcohol.

Real Life

 * After former Democratic Representative from Texas Charlie Wilson stopped drinking for health reasons, he still kept a single bottle around for a really special occasion. He consumed it upon the announcement that the Soviets were pulling out of Afghanistan (Giving aid to the rebels fighting there had been his goal for some time).

Western Animation

 * In The Venture Bros. episode "Dr. Quymn, Medicine Woman", the titular doctor wears a crystal necklace throughout the episode. We find out after she suffers an epileptic seizure and her home burns down that it's her last cigarette, which she proceeds to smoke to deal with the stresses of the evening.