Imagine you’re on a long road trip. Is there a word for that other driver who sets the pace for your car mile after mile? Road buddy, perhaps? A Rhode Island caller says her family calls that driver a Follow John. Social psychologist Stanley Milgram applied the term familiar stranger to denote the people we recognize because we regularly share a common physical space, such as a bus stop or a park, even though we don’t interact with them. This is part of a complete episode.