HFMF 

Abbreviation for heinous fuckery most foul.

Guy1: Someone stole my car!

Guy2: HFMF.

Guy1: ...What?

HFMF by Dalek Sec November 20, 2007

gl hf mf 

An extended version of the traditional "Good Luck, Have Fun." The additional "mf" means "motherfuckers" Therefore, its a way to be Bad Mannered at the start of a game. Best used with capslock: "GOOD LUCK, HAVE FUN, MOTHERFUCKERS!"

Bob: gl hf mf!
Fred: You Too!

gl hf mf by TheMotherF-er December 29, 2010