The relatively new and shocking phenomenon of when you meet someone through Facebook, sometimes from all over the world, and you find out that you went to school (elementary, Jr. High, High School, etc) with them, or they are friends of your parents from many years ago, or they worked with you at job in the past, and you never knew it, and would never have met them without Facebook. And, then they become a good friend. Basically, the beauty of Facebook.
"I met the most incredible person on Facebook."
"Oh really, who?"
"Well, he's the same age as my Dad, and he lives 3,000 miles away. We met through a group that we are both in."
"Turns out he KNEW my Dad, before I was even born, and I never even knew him!!! I found him before my DAD did!!! Weird, huh?"
"That's so cool!"
"Yeah, it is, and now we are really good friends! Six degrees of Facebook for you..." *laughing*
"I know, right?"