I generally play with 2 friends so often we will get put with a single. 9 times outta 10 this person is great to golf with and usually pretty outgoing.
However about a year ago our group got put with a guy whom after the ranger let us know he'd be playing with us we shook hands, he said hello....and that was the last peep outta him for 18 holes. We have gotten used to having an unknown 4th with us so we try to talk them up a bit to make them feel comfortable with us give them a few "nice shots" or "good putt" whatever the situation may warrant , talk some local sports on the tee, general guy stuff I guess. This dude didnt say a thing... not even a mumble or grumble. Shook our hands after 18 and walked off all silent. Was silly weird.