means Laugh out Loud, Just kidding even though it really should mean LOL, jokes. but it doesnt. thees two words are often used together in jokes, you say somthing that is not true then write, LOL, jk somthing ellse funny.
it has been used widely to create groups on facebook,
i'd take a bullet for you LOL jk, that would kill me
Lets Run Away Together... LOL, JK I have Asthma
I would carry you to the moon and back...LOL jk, your fat and i'd die
I want you, LOL jk, you wish