A fork of Rural Dictionary
"Sung-Joon" is a slang term for someone who purposefully irritates others whilst acting oblivious to his/her actions.
Person X posts a photoshopped picture of Y to irritate him/her Y: "why did you do that?!" X: "ha...what are you talking about?" Y:"You know what I mean!...your such a Sung-Joon" Another example: Person X falsely claims to have beaten up person Y in a sad attempt to gain clout from his/her peers. Y: "Why are you telling people that you beat me up?" X: (Giggling)"because I did" Y: "What are you on about? Your such an SJ!"