A typically AFB person is a person who acts just plainly brainlessly..AFB at first derived from the expression "afk", but "afb" stood firstly for a person , who wasn't afk, but acted just as retardedly as if he/she would've been it.
The AFB expression is used by 1337 speakers, who applies their 1337 speaking abilities to their everyday 1337'ish lifes.
doing something other then starring at your internet window.
User 2: um ok im going afb
User 1: blah blah fuck im dead u ass hole where did u go?!
User 1: HELLO?!
User 2: O im sorry i was watching a movie, NOT caring what u say. AND FUCK U!!!
UAFB - Univited attack from behind as described above.
IAFB - The girl first indicates that your advances are welcome/backs into you.