That's a new one on me!

that's a new one on me

That is something I was not aware about or did not know. A: "Yeah, Jeff and Anthony have been going out for a few months now." B: "That's a new one on me. I thought they were just friends." You aren't allowed to dump your grass clippings here? Well, that's a new one on me.
See also: new, on, one

That's a new one on me!

Inf. I had not heard that before. Bob: Did you hear? They're building a new highway that will bypass the town. Fred: That's a new one on me! That's terrible! Sue: All of us will have to pay our taxes monthly from now on. Mary: That's a new one on me!
See also: new, on, one