one
mod. having to do with something unique or special. (Similar to a definite article.)Tracy is one fine cook.He was left with one powerful hangover.Hank? Now there is one ugly son of a gun for you.
That's a new one on me.
sent. “That is truly amazing.”; “I did not know that.”A machine that copies in four colors. That's a new one on me.A talking camera? That's a new one on me.