A response to a rude question where someone is asking for personal information they are not entitled to. Nunya is part of a burn to follow such a rude inquiry.
Question: How much did you pay for that?
Answer: Nunya
Question (perplexed): Nunya, what's that?
Answer: Nunya fucking business
A short and blunt way of saying 'none of your business', it can be used in reply to any and every questionpossible. If a further 'pardon?' is asked, a lengthier reply of 'nunya business' can be used.