what's it to you, him, her, etc.?

What's it to (one)?

What does one care? What business is it of one's? I pay my rent and my share of the bills—what's it to him how I spend my money otherwise? What's it to them what I do on the weekends? That's my time to do as I like! A: "Do you mind if I do yoga in the living room?" B: "Of course not! What's it to me?"
Farlex Dictionary of Idioms.

what’s it to ˈyou, ˈhim, ˈher, etc.?

(informal) (said when you are annoyed) you, etc. have no right to know something; what does it matter to you, etc: What’s it to her how I spend my money?
Farlex Partner Idioms Dictionary
See also:
  • What's it to (one)?
  • What's it to you?
  • What’s it to you?
  • what's up
  • What's up?
  • What’s up?
  • what's cooking
  • What's cooking?
  • What's good (with you)?
  • What’s really good witcha?