눈(이) 삐다 is an idiom which means "to look incorrectly or amiss (with accusing nuance)" 눈(이) 삐다 : 뻔한 것을 잘못 보고 있을 때 비난조로 이르는 말. 눈 삐었네. You looked incorrectly!

Hello! I'm guessing you heard this from a Korean movie(or maybe not, can't be too sure). Literally it means, 'you sprained your eyes.' Doesn't make any sense in English right? It doesn't make any sense in proper Korean either. '삐다' which is used in the sentence you provided means 'to sprain,' as in to sprain one's ankle. One can't sprain one's eyes. So when someone says 눈이 삐었네 they say it to emphasize that there was a huge mistake/fault in something that someone has done and that they are dissatisfied by it. This is an extremely rude way to show one's dissatisfaction. Unless you're really mad at someone and don't mind what he/she might do to you after you say '눈이 삐었네,' I would avoid using this expression at all costs :) Let's say someone borrowed $1000 from you, and gave you back only $900 telling you that it's a thousand dollars. After counting again and checking that he/she is $100 short, you tell this person that he/she is $100 short and this person keeps insisting this is the correct amount. Here, you could say, '눈이 삐었냐. 다시 세 봐(what's wrong with you, count again.') Or let's say you had a pop quiz in class and the teacher told you to grade each others' paper. Let's say the guy sitting behind you graded yours. Say you only got one question wrong but whoever graded your paper said you got two wrong. You could say. 눈이 삐었네. 다시 채점해봐(What's wrong with you? Grade it again)