keep under one's hat
Preserve the secrecy of something, as in I'll tell you about it if you promise to keep it under your hat. This usage alludes to hiding a secret in one's head, covered by a hat. [Late 1800s]
Words nearby keep under one's hat
How to use keep under one's hat in a sentence
Added to drinking water at concentrations of around one part per million, fluoride ions stick to dental plaque.
In his view, a writer has only one duty: to be present in his books.
Yet this, in the end, is a book from which one emerges sad, gloomy, disenchanted, at least if we agree to take it seriously.
“The institution of marraige [sic] is under attack in our society and it needs to be strengthened,” Bush wrote.
The fear of violence should not determine what one does or does not say.
Practise gliding in the form of inflection, or slide, from one extreme of pitch to another.Expressive Voice Culture|Jessie Eldridge Southwick
He alludes to it as one of their evil customs and used by them to produce insensibility.
There was a rumor that Alessandro and his father had both died; but no one knew anything certainly.Ramona|Helen Hunt Jackson
Truth is a torch, but one of enormous size; so that we slink past it in rather a blinking fashion for fear it should burn us.Pearls of Thought|Maturin M. Ballou
Under the one-sixth they appear as slender, highly refractive fibers with double contour and, often, curled or split ends.A Manual of Clinical Diagnosis|James Campbell Todd