From Wiktionary, the free dictionary
See 무엇 (mueot). Like northern dialectal 무스거 (museugeo), it appears to be a more conservative descendant from the original term.
무스그 • (museugeu)
- (Hamgyong, Yukjin, Yanbian, Russia) Dialectal form of 무엇 (mueot, “what, something, anything”)
2016 February 26, 황문자 [hwangmunja], “춘향전 [chunhyangjeon]”, in 한국구비문학대계 [han'gukgubimunhakdaegye][1], 카자흐스탄 아스타나 [kajaheuseutan aseutana]:아니, 무스그 보는가?”- ani, museugeu boneun-ga?”
- What are you looking at?