If you learned the word "쉬먀" from 무한도전 (or that kind of TV show) 쉬먀 is a word to copy chinese language. (just like you add "Desu" to copy japanese or "Imnida, Sumnida" to Korean.)

there is no word called 쉬먀 i think someone mistyped it or someone's name only i can imagine is 쉬먀 resembles '쉬마' 쉬마 means 'i'm going to relax ' 좋데 means 'oh it says it's good ' 'someone says it's good '