This is none of your business in korean. There are more than 1 way of saying this. 상관하지 마세요.(normal but bit offensive) 참견하지 마세요. (similar to the first one) 당신이 상관할 바가 아닙니다. (not really used) 신경쓰지 마세요 (most polite way) 너나 잘하세요 (most rude)

so word 남이사 means 'none of ur business'? I hear this at first....it sounds unusual )))

this is the one that I like the best.. 남이사