Facebook amnesia 

When people from earlier in your life whom you hated decide to friend you on Facebook as if you're old friends.

"David must have Facebook amnesia. He friended me even though I hated that little fucker back in high school."

Facebook amnesia by TheLongRanger2 December 3, 2009

Facebook Amnesia 

A condition of thoughtlessness which occurs when you open up Facebook and forget what you are doing. It is usually temporary, and the person will eventually awake as if out of a stupor. Those who suffer from it are unable to retrieve information and instead fall into a state of oblivion. The most common symptom is mental blankness where the victim descends into a deep state of incognizance.

Danny: Dude, can you see what time the open mic is at?
Rob: Sure man, lemme just check on Facebook.

15 minutes later....

Danny: Bro! What the hell have you been doing for all this time?!
Rob: Oh, I, uh...just looking at some pictures of this girl who's a friend of a person I found on the wall of an acquaintance from middle school.
Danny: Broooo! Shit, stop it, she's like 16. You've got Facebook Amnesia! Now go and check the event page.

Facebook Amnesia by MonteCristo8 August 26, 2013

Facebook Amnesia 

A state of confusion found while looking through your news feed and seeing posts from facebook friends that you can't even remember adding. not remembering why they are connected to you, where they came from, where they live, or in what capacity you've met them in real life.

upon viewing his news feed he sat back bewildered, asking himself “who the hell are all these people? i don't remember any of them!” he realized he was suffering from facebook amnesia.

Facebook Amnesia by CurvedMirror April 17, 2014

Facebook-Amnesia 

When you get on the computer to do something productive, but instead you instantly go into auto-drive and log onto Facebook and completely forget the real reason you even got on the computer.

Man, I was going to write my 10 page english essay until I was hit by brick wall of facebook-amnesia!

Facebook-Amnesia by Glendora July 7, 2011