friend by association 

A person who is your friend, but only because he is one of your friend's friends. It doesn't really matter how much you like him, or how often you converse, he is still your friend by association. But he can only be a friend by association if you have met him, (and not just heard about him) and talked to him.

Erik is Chris's friend. Josh is Erik's friend. Erik introduced him to Chris. Chris greeted him. Josh is now Chris's friend by association, and vice versa.

friend by association by Christophart August 23, 2010

Best Friend By Association (BFBA) 

When you meet a friend of a friend that you have heard so much about them that you feel that you already know them as a person. Feeling that you are already best friends even if you have only met them twice.

Ex. Your mutual friends sharing inside jokes and then you all share the inside joke, even if the third party was not present when the said joke was made.

Best Friend By Association (BFBA) Scenerio:

Friend: Hey this is my friend Bob

Friend of a Friend: Oh your Bob? I've heard so much about you!!!! (Super excited, and might even share an inside joke that she heard from your mutual friend)

Bob: It's great to finally meet you too, We are like Best Friends by Association (BFBA)

Best Friend By Association (BFBA) by Bad Ass Unicorn December 5, 2012