new one on

a new one (on me)

Something I was not aware or informed of or knew nothing about until just now. A: "Yeah, Jeff and Anthony have been going out for a few months now." B: "That's a new one—I thought they were just friends." Having to pay for the water you use in your house is a new one to me—is that an American thing or something?
See also: new, one
Farlex Dictionary of Idioms.

new one on someone something

that one has not heard before and that one is not ready to believe. Bob's talk of poverty is a new one on me. He always seems to have plenty of money. The firm's difficulties are a new one on me. I thought that it was doing very well.
See also: new, on, one
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • a new one (on me)
  • a new one on
  • a new one on me
  • (that's) news to (one)
  • That's news to me
  • (it's) news to (one)
  • it's/that's news to me
  • news
  • That’s a new one on me
  • That's a new one on me!