that's one on me

That's a joke at my expense, as in And after all that discussion they didn't show up—that's one on me. This phrase must be distinguished from that's a new one on me, which means “this is the first time I've heard of or seen that” (as in A checkerboard rug—that's a new one on me). Both idioms can be used with other personal pronouns (for example, that's one on you) and date from the early 1900s.

Words nearby that's one on me

that'll be the day, that's, that's _____ for you, that's about the size of it., that's how the ball bounces, that's one on me, that's right, that's that, that's the beauty of, that's the ticket, thataway