Short for "affirmative" and use much like "yes" or "indeed". This primarily from the Battletech universe (and the Mech Warrior games) where Clanners use it. It's still used by fans, though use is dying out.

AFF - Away From Facebook.

When you are not AFK (away from keyword) but only AFF (away from facebook) so you can be doing other things online.

The times at which you are not on facebook (i.e. doing work, watching porn and playing COD).

Aff is short of Affirmative. It Helps a lot while playing team shooters.

A Noun Discriminating Against African People

AFF is an abbreviation they use for 'Accelerated Free Fall' and refers to the 9 stages involved in learning to become a solo skydiver. Skydive Oz Australia runs AFF Courses weekly - it's believed the term originated from there. The AFF stages are most commonly found within the solo skydiving 'A' Licence course. The AFF course facilities are found at Moruya Airport near Batemans Bay NSW 2536 Australia. The abbreviation is used amongst skydivers as a noun - You just AFF'd that up. You're a level 6 AFFwit.

Away From Facebook

it started to be used after people started being on facebook too much and not doing work. So if they mean that they are still at the computer but must close facebook to do some work, they use AFF

After Fuck Fart