People with this affliction, verbalize their stream of consciousness.
Often found in old professors, men on first dates, and homeless people on street corners. It is futile to try to stop it by interrupting, changing the subject, or ignoring, so don't try.
It is not all bad because it is easy to learn a lot about the person simply by opening your ears. Don't forget that so much of what they say may not be the truth, but everyone knows that the truth is definitely not the only way in which you can get to know someone.