Pretending that you don't know every single detail about a Facebook Friend's life so that you (a) do not seem like a stalker or (b) have something to talk about. Also an antidote for friends that over-share on social media.
(1) I had to feign Fabnesia when I was talking to my old girl friend so she thought I wasn't checking her out on Facebook! (2) If I didn't have Fabnesia, I would have had nothing to say to him!
Wow man, that turn changer is radically farnesque. you have no idea. it makes my mind farnesquetically implode with thoughts and idioms of farnesticology and farnesticism. wow. farnesque. yeah.