When people from Lynden, Washington remain in Lynden after
highschool and then proceed to date/marry in the same
small pool of other people who remained in Lynden after
highschool.
Linda, "Dubtehfuck, what are these engagement photos of
Billy and Sally doing in my newsfeed?!"
Marcus, "Oh, didn't you know they both stayed in Lynden after graduation, never branching out into the real world, and then decided to date?"
Linda, "What a textbook example of Lyncest! I'm going to go throw up in my shoes now."