A j4ker (pronounced "jacker") is someone that uses "jk" or any other abbriviation in txting, comments, email, youtube, pretty much fucking anywhere.

abriviation for j4ker: jkr (only for you j4kers out there!)
J4ker: lolroflmfao jkjkjkjkjkjkj lolololololololo omg wtf bbq! :-D ^_____^

regular guy: Yo man, what the hell are you saying? You stupid j4ker!

j4ker: i b no jkr! *___* mf! :-D
by blu3hat October 6, 2010
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