1) LOL, JK - The 'textual communication' version of "Laughing Out Loud, Just Kidding". Popularly and incorrectly theorised to to actually mean "Laughing Out Loud, Joke"
1: Hey baby, here have a turn on COD... LOL jk, go back to the kitchen
2: gonna get drunkkkkkkkkkk this weekend!!!! LOL jk im muslim
Lily: Dude, Sally needs to stop making out with everyone.
Mary: I know right! She's such a whore. LOL jk but seriously though.
Example 2
(John is driving his girlfriend's bug)
Bill: Hey, John, can you give me a ride?
John: Sure, man!
(they walk to John's car)
Bill: Whoa. Dude, that is one fruity car. Haha just kidding. . .but seriously though.
John:. . . that's my girlfriends car. .
Something PewDiePie says when he gets caught doing something stupid. For regular people, it's used to express someone making a joke, then laughing and saying that they're kidding. It's usually a mean joke.
If I hear one more person on the Internet say "loljk" after insulting me, I'm gonna scream!