I just use my common sense. What KarissaMann05 replied is true. I usually tell my passenger to wait until I feel comfortable enough to listen since if there are too many cars around, it's important for me to pay attention to the road. If there are not many cars around, I do what green427 said exactly.
My friend was fucked up because he swerved while he listened to the very talkative passenger so the cop stopped him and found out that the friend was on warrant for failing to appear in court for his previous DUI case so he was arrested right there.
When I drove, oh boy, that same passenger wouldn't shut up.