This is an acronym for the phrase "a free kill". Commonly used while talking about online players which are non responsive. Coined by online computer game players who needed to inform others not physically present of their period of absence.
This acronym was a short way communicate to other people that a person was not there, rather than type the entire phrase. The relatively slow speed of typing is likely to have caused the formation of this and many other acronyms. The word is common jargon among many video game players.
Source : "Dude, he's afk. Just let him die." -Friend on Xboxlive
Last modified: 5 December 2011