Hm... April's answer is good. But I'm kind of old LOL though, I sometimes use that. Like..."이야~ 너 임마 아주 그냥 오늘 패션이 제도로야, 킹왕짱이여 ....! " like that.... And this sentence means, " Yo ~ dude! your fashion is really really gorgeous, awesome today...!" And here's detail. 킹 = King , 왕 = 王 = King, 짱(kind of Korean slang) = the best. So it can mean "Really really awsome" or something like that. Of course teenagers often tend to use it but everybody can use it too for fun.

킹왕짱 is a expletive word... For example - 'very good' 'very' delicious , 'very' nice , 'super' strong usually this word is used by tenagers.