A description for a vicious, crazy, rude, and stupid person who doesn't interact well with others. Nayoung's are usually violent, and when they are upset, they like to take it out on others. Nayoung's should be considered armed and violent, and shouldn't be approached.
Girl 1: Who is that over there?
Girl 2: Oh that's Nayoung
Girl 1: I think I'll go say hello
Girl 2: NO DON'T! She's crazy and usually carries weapons. I wouldn't approach her.