F/O usually stands for Fictional Other, which is a term often used by Self-shippers, mainly on Tumblr.
You can have romantic, familial and platonic F/Os!
Self Shipper 1#: Yo, I got a new F/O!!
Self-Shipper 2#: That's so cool, who are they?
Self Shipper 1#: It's Peter Parker from The Amazing Spider-Man, 2012!
short for the First Order the first order is the military embodiment of the dark side in the star wars sequel generation the leader of the the first order was mostly supreme leader Snoke then his apprentice kylo renkilled him and now he is the new supreme leader.
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.