bus face
The appearance and demeanor a person possesses that makes them instantly recognizable by the people on the bus (or other forms of public transportation) desperate to have a conversation. A person with bus face usually appears pleasant, friendly, thoughtful and patient, and most importantly, ready to listen to all the way too personal and/or awkward stories that other people who ride the bus have no one else to tell.
Suzie wanted to sit quietly on the bus ride to school, but the old man sitting next to her saw her bus face and forced her into a 20 minute long conversation about constipation.