Secondhand Spoke (S12E15)

Peter takes up smoking to get extra breaks at work. It makes him look so ill that he gets a job as the frontman of an anti-smoking campaign, but he has to carry on smoking to keep the job. Chris is being teased at school so Stewie offers to hide in his backpack and feed him smart putdowns. But when Stewie's wit makes Chris so popular he's elected class president, he won't let Stewie out of the backpack. (BBC)