Jewish people have a great Yiddish term to describe one of life’s important relationships: the parents of your child’s spouse, or your co-in-laws: machatunim. There’s no good English word for it. Our language also lacks a term to describe another sometimes-tricky relationship: the friends of your friends, those people you see once a year, at your pals’ holiday parties.

Who are these people? And why do your friends like them? Or, conversely, why do your friends like you, when the rest of their pals are such winners?