thanks sehrish ya i guess there is no such translation for this term but the concept can be translated ..
I TAKE THE FIFTH is not something that you say in order to tell someone you are not going to answer this question …chahe woh kisi bare main bhi ho…???
when ever i dont wana talk or answer anyone about anything weather its about me or its about the person i m talking with or any general thing..i say i take the fifth 
like i m refusing to answer…
btw it can only use in legal concept like in courts as u dont wana asnwer…???
or jaise i m uisng waise bhi karsakte hain 