I host entire conversations with myself with varying people. I argue with people I don't like, chitchat with people I do, give advice to close friends, and tell Glenn Beck he's an idiot while in a grand auditorium full of people.
I can talk to myself for an hour or more, but I lose it as soon as I break the 4th wall. The moment I bring up, in conversation, anything with having to do with talking to myself, I lose the momentum and just stop and return to what I was doing.