Yes-King is a quick and witty expression to say "Yes" to someone, while dissing them up at the same time. The insult from saying "Yes-King" is to infer that they are also a Wong-Fung-Ngai, which is very insulting in Chinese.
Juan-Pablo: Yo are we going to hit up some flylice my flend?
McLigz: Yes-King...Who are u mang? Dun be so lay!