The acronym for the phrase 'Fuck It I'm Young'. It's infinitely better than YOLO and much easier to pronounce, obviously.
Matt: You shouldn't eat pumpkin soup whilst recording the podcast mate
fuck it i'm young
more commonly used on the internet that in real life.
friend- you out tonight?
me- i wasn't going to but fiiy!
Fuck - It - I'm - Young
Justification for doing anything immature, stupid, dangerous or ridiculous
Jimmy: I dunno man, do you really think you should fuck this dead hooker we found here in the forest
Jimmy: Hmm didn't think of it like that, Seems legit