Nff stands for (Not Funny Fucker)
If some one is making a lame joke. You tell him NFF (not funny fucker)
NFF is a nice way of saying Not Fucking Funny
You and Bozo are NFF
She's pregnant, it's NFF
"New Found Friend"
When you go away on holiday or college trip, and one of your friends spends his time ignoring you to speak to other people and trying to be popular.
"Towle's NFF'ing it again"
No Fault Found
Technical support term meaning all is well, the end user is to blame.
See also PEBKAC
NFF, EU hasnt got a scooby-doo.
Not Family Friendly" -- email subject warning code for "Don't look at this in front of the kids -- and use judgement about your significant other
Subject: web comic link -- 2 funny, NFF