뎨둉 죄송하다는 뜻의 표준어입니다 ( 농담 ) 신조어 입니다. The standard language meaning is sorry (죄송하다) It's a joking or playful word. Neologism http://kin.naver.com/qna/detail.nhn?d1id=11&dirId=11&docId=158817721&qb=646o65GJIOutkOyXkOyalA==&enc=utf8§ion=kin&rank=1&search_sort=0&spq=0

It appears to be something cutesy or cool. Hmm...interesting...

I'm sorry. It's not Korean word. Could you explain where did you see this?