Simply go to your happy place and enjoy it. I finished a 4 day a few weeks ago with a guy like that. You couldn't get a word in edge wise and if I could have slit my wrist with the plastic fork from my lunch I would have. The guy was highly bright but it was a 4 day marathon of free form thought and prose. Finally on return from the west coast I he told a four hour story of how he met his wife. This somehow transitioned to how he took multiple road trips in the Air Force to go cross country, snow ball fights, water balloon fights, his kids are toolbags, and his favorite colors. Somewhere over western TN as the sun was setting I just looked at him and totally forgot myself. I uttered something along the lines of "Biff, I don't know what the F*&$ you're talking about, but you f*&$ing lost me back over the rockies". He just kind of looked at me for a second then continued unabated.

That's why you upgrade when the time comes. I don't ever remember an FO talking my ear off in previous lives. But Captains, you just have to roll with it. Now that being said, down below 10,000 ft. in sterile cockpit, just start asking him after every ATC transmission "Was that for us?". Pretty soon he will be paranoid and stay focused on ATC and stay shut until you park at the gate.