Its an abbreviation for RussianKilla or RussianKiller.
Yo did you hear about RK who is now locked up?
Rk is usually used in a Roblox game called yba (your bizarre adventure) which is a jjba ( Jojo's bizarre adventure) game and it means when someone attacks or kills you out of the blue or for no reason. Some goofy ah people that opinion doesn't matter say " rking doesn't exist it's a fighting game" but they just simply can't accept the fact that people might be afk ( away from keyboard ) or just want to chill with their friends in a fighting game
That guy keeps rking me. I did nothing to him, he just wants attention and someone to bully
he is a very handsome guy, even though he has a sharp chin it is the key feature to his personality. Rk is Rk when he has a sharp chin!
hey you must be RK? you have a sharp chin