In a room of software developers, another dev and myself sometimes chitchat if we find something interesting. With no explicit declaration, we limit the talk to just a few seconds and only if it is really interesting and insightful.
Recently another dev moved into the room and he chit chats way too much. He doesn't share our high standards of importance, and doesn't know when to stop. I don't want him to be a part of our chit-chat routine because he is ruining it Eternal September style. I know that I could just stop chit-chatting with the original coworker, but we both gain insight and learn from our exchanges. I don't want to lose that.
I tried using Instant Messaging for the chit-chat as opposed to speech, but it is too cumbersome, slow, and disruptive: we can't just start and be done in a few seconds. The half-duplex nature kills it.
How can I tell one coworker in the same room that we respect him and accept him and we are friends with him, but when we're coding don't bother us even if it appears that we are bothering each other?
EDIT: To be clear, I really do like the guy. It's just that he does not know when to stop talking, and his "wow, this is interesting" threshold is two orders of magnitude below ours'. I don't think that every /. story warrants a discussion, but heartbleed does. When we're not working, such as eating, then I really do take an interest in what he has to say. That doesn't mean that I need to let him interrupt my work several times per day, even if I allow someone else that privilege.