It is the acronym for the word "Shit Load Of Fuck"
1.) It basically saying that something is truly awful, beyond bullshit, or if someone is full of himself i.e. False sense of pride, Lies, gloating, etc.
2.) Terrible, Horrible, Trashy, Filth
Inspired by James Rolfe a.k.a "The Angry Video Game Nerd" use of saying the phrase "Shit load of fuck" in his reviews
1. This game is...God I'm so tired of saying it so many times, it basically S.L.O.F
2. The new rules for tournament is just a piece of S.L.O.F
3. "Dude you are just full of S.L.O.F. Get out of my face"
4. Zelda CDI games a loads of S.L.O.F