A new one on me - Idioms by The Free Dictionary
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.
a ˌnew one on ˈme a story, joke or piece of information that you have not heard before and which you may find difficult to believe: Butter that always stays soft — that’s a new one on me. ♢ No, I’ve never heard that story before. It’s a new one on me.