FUSFM 

Fuck You so fucking much.
Because there is a need for redundancy with effing with an effer.

person 1: Fuck you.
person 2: Fuck You too. FUUU2
person 1: Fuck You so fucking much. FUSFMMMMM
person 2: Fuck you so fucking mucher
person 1: Fuck you so fucking muchest
person 2: fuck you so fucking most!
person 1: Fuck you so fucking mostest
person 2: Fuck you so fucking mostestest
person 1: FUCK YOU SO FUCKING MOSTESTEST!!!!!! that's in capslock and with dozens of exclamation points. i win.
person 2: darn it.

FUSFM by google chrome is the shit July 27, 2010

FUSMC

Fuck yoU, Suck My Cock

Yet another acronym brewed up by Marines, this is only to be used when dealing with motivated, or "moto", fuckwits who blue falcon everyone else with their faggotry.

Gunny: All right dicksucks, until we find that lost pair of NVGs, libo is secured for the rest of the weekend. I don't give a fuck if you, your wives/GFs or kids planned a weekend getaway. You'd best find my NVGs!

*finds them in his seabag*

Gunny: Ha ha! That was silly of me! Weekends, rah?

LCpl: FUSMC Gunny.

FUSMC by Uncle Sam's Misguided Child October 13, 2011

Fusome 

Its not awesome, its not nice, its not wonderful, its just fusome (fucking awesome)

Its THE word, nothing better than it.

Kelly Kyle is the most Fusome girl ever <3

Fusome by acostarican September 26, 2010

Fusf 

Fuck You Shit Face

Hey Marty, FUSF!
Hey Troy, FUSF!
Who is Joe? FUSF!

Fusf by Bad Stuf May 16, 2018

FUSF 

Fuck U Shit Face

When your friend is acting a fool on the gram, you type FUSF to put them squarely in their place.

FUSF by Bad Stuf May 8, 2018

FUSIMUD card

The card left behind when the postmen cannot deliver your package.

Fuck You Sorry I Missed U Dickhead

OH great Australia Post left me the FUSIMUD card

FUSIMUD card by Habura123 June 18, 2016

FSFM 

Feel Sorry For Me:

A iteration of FML, not usually used by the actual poster, but by a reader of the post. Often don't by adolescent girls (or ones with that mentality) who are craving attention and wanting someone to say "aww, I'm sorry to hear that"

did you see jackie just posted "JOHN BROKE UP WITH ME!! FML" I think she meant to put FSFM.

FSFM by trollomatic May 13, 2009