I'm looking for a humorous short story where a human lives with aliens as one of their own, as part of a cultural exchange. He and his host have to pretend he is one of them. Against all odds, he is the one selected from his adopted culture to live with yet another alien culture. It was probably written in 1970-1985. I thought it was in a Terry Carr "best sci-fi of the year" book, but can't find it, so may be in a different collection.
Probably "Trial Sample", a short story by Ted Reynolds, which was also the answer to the question What funny story had humans in an exchange program with pterodactyl-like aliens?; first published in Isaac Asimov's Science Fiction Magazine, June 8, 1981, available at the Internet Archive; you might have read it in Terry Carr's anthology The Best Science Fiction of the Year #11.
Mayor Bleewooe nodded his head wisely for a moment, scratched his left shoulder blade with the tip of his right wing, and then enunciated solemnly:
"Small one, you must be aware of the method by which sentient races make, or fail to make, viable relationships with one another. I refer, of course, to the lottery system, by means of which one randomly chosen individual from a given species is selected to live a standard year as a citizen of another world. . . ."
Paul could say nothing. The mayor’s roundabout words certainly sounded like the whiplash of descending doom.
Mayor Bleewooe was methodically continuing. ". . . so if the representative individual and the society he has joined can mutually tolerate each other for one standard year, then trade and diplomatic relationships can be entered into between the two species in question. But . . . " and the mayor drew himself up austerely, "if for any reason, not, then . . . not!"