what's it to you?
what does it mean and when do people say it?
This is what I believe I have heard on the radio.
A reporter was questioning a man his involvement of something that he allegedly did.
The man just kept throwing this expression back at him, as if saying "that's none of f*** business."
I did a little bit of searching and couldn't get any info about this expression.
Would you explain the meaning of this expression and suggest other possible situations where it may also be used?
Thanks a great deal.

Question

what's it to you?
what does it mean and when do people say it?
This is what I believe I have heard on the radio. 
A reporter was questioning a man his involvement of something that he allegedly did. 
The man just kept throwing this expression back at him, as if saying "that's none of f*** business."
I did a little bit of searching and couldn't get any info about this expression. 
Would you explain the meaning of this expression and suggest other possible situations where it may also be used?
Thanks a great deal.

Answer

"What (significance) is it to you?", meaning "Why is it your business to know?" or as you correctly guessed, "That's none of your f**king business."

Use it when you don't see why someone should be asking questions about who you are or what you're doing (when they're being nosey!) - but remember it is slightly aggressive.

Answer

I agree with fdmaxey. 

"what is it to you" may also mean "what good will it bring you?", or "why do you want to know?" when expressing annoyance. 

ex. 

"I heard you and your wife yelling at aech other last night, mind to share what happened?" 

--- "what is it to you?" (suggesting that "this is my own problem, keep your hands off it."). 

:)

Answer

It means "Why is it important to you?"
"I see you're going out with that new boy a lot."
"What's it to you?"

Answer

It's throw away line that you say to people who are interfering in your life.

Answer

"What is it to you" it is my name used at Italki, Wozitoya, an American slang simply means mind your own business