Lk

Lk is short and slang for little kid with a hint of lazy kid used by the cool kid and his bud just to be as annoying as possible. Often said in hearing distance of victim(or the lk)

Cool kid: Look at that lk over there, such a retarded brat.
Cool bud: Yeah such a kid.

WTF

When your teacher or mom accidentaly types you this and you ask what it means:
Response: Well that's fantastic

Son: I got kicked in the head today by a bully...
Mom: WTF!
Son: What does WTF mean?
Mom: Well that's fantastic