new one

that's a new one

That is something I haven't heard before. Usually in reference to an unusual excuse or explanation, often said sarcastically or ironically. She said she couldn't turn in her assignment because her parakeet flew off with it out the window? Well, that's a new one. That's a new one—I've never heard of someone asking not to be paid for their overtime work before.
See also: new, one
Farlex Dictionary of Idioms.

new one

see under that's one on me.
See also: new, one
The American Heritage® Dictionary of Idioms by Christine Ammer.
See also:
  • a mystery to (one)
  • a turn of phrase
  • a piece of the action
  • a piece/slice of the action
  • appear to
  • able to do
  • able to do it
  • a change of heart
  • a bit of the action
  • bit of the action
References in classic literature
[1289a] rather to treat of what is common, censure those under which they live, and extol the excellence of a particular state, as the Lacedaemonian, or some other: but every legislator ought to establish such a form of government as from the present state and disposition of the people who are to receive it they will most readily submit to and persuade the community to partake of: for it is not a business of less trouble to correct the mistakes of an established government than to form a new one; as it is as difficult to recover what we have forgot as to learn anything afresh.
At last he drove me quite without a check-rein, and then sold me as a perfectly quiet horse to a gentleman in the country; he was a good master, and I was getting on very well, but his old groom left him and a new one came.
My four Sons and two orphan Grandchildren had retired to their several apartments; and my wife alone remained with me to see the old Millennium out and the new one in.
And having entered on the path of definition, of which he was fond, Napoleon suddenly and unexpectedly gave a new one.
Marry him, ma'am, to the new one with the utmost speed and impetuosity which the law will permit.' I hate Mr.
If I have any secret, it is - no new one; and is - not what you suppose.
By chance, however, the first boot which was procured for him was a new one and, therefore, useless for his purpose.
The plan itself is not a new one. It was worked out at Hampton Institute, but it was done at Hampton by white men.
O, go way!--why didn't Sally get out de best tea-pot,--de little new one, Mas'r George got for Missis, Christmas?
At the end of ten seconds each man had struck twelve or fifteen blows, and warded off twelve or fifteen, and no harm done; then a sword became disabled, and a short rest followed whilst a new one was brought.
And often they got so interested listening, that when he had finished they found their fire had gone right out; and they had to scurry round to get more sticks and build a new one.
With this sword only it is possible to kill the Serpent, because even if its blade breaks a new one will grow again for every head the monster has.
It is a kind of assemblage of societies that constitute a new one, capable of increasing, by means of new associations, till they arrive to such a degree of power as to be able to provide for the security of the united body."
I say at once there are fewer difficulties in holding hereditary states, and those long accustomed to the family of their prince, than new ones; for it is sufficient only not to transgress the customs of his ancestors, and to deal prudently with circumstances as they arise, for a prince of average powers to maintain himself in his state, unless he be deprived of it by some extraordinary and excessive force; and if he should be so deprived of it, whenever anything sinister happens to the usurper, he will regain it.
Old friends cannot with impunity be sacrificed for new ones.