It's an abbreviation for a game: Friday Nights Funkin'
*Me: Dude, I just beat FNF on the first attempt
*My friend: That's sick!
Friend:you going to this party tonight
Me: yea girl I’m FNF I’m outside all summer, I’m hoppin out at red lights twerking on them headlights
FNF is short for Friday Night Funkin. Friday Night Funkin is a game. A rhythm game. The Protagonist is Keith which is called Boyfriend/Player. Ashley, also known as "Girlfriend" She is not a Protagonist or Antagonist.
Keith and Ashley go on adventure. Exploring FNF Mods.
"I love FNF"
" FNF is fun and relaxing but sometimes scary"
Girl 1: I want to go out, but I’ve just been down cause I think my man talking to another girl
Girl 2: Im Fnf that means I don’t have to worry about a fuck nigga cheating