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.
PH1R3 - Like yeah? TOTALLY!
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.