Friendship Incest Syndrome (FIS)
Friendship Incest Syndrome is an occurrence where you have a group of friends who have all dated and broken up with the same people, then you are eventually forced to be friends with an ex because they're still in your circle of friends - in fact they're probably dating one of your friends by now. It effects a small # of people, likely living in Southern California. It extends to Frenemies who have removed themselves from the circle whom you can never fully get away from.
I'm going to a concert tonight, oh jeez, Robin & Joe are going to be there...Friendship Incest Syndrome (FIS).