schtum

keep schtum

To remain silent; to not say anything. (Used especially when by saying something, especially at the wrong time, one would cause trouble or difficulty for him- or herself.) Primarily heard in UK. It's better to just keep schtum when the boss starts flinging accusations than risk further incensing him.
See also: keep, schtum
Farlex Dictionary of Idioms.

keep ˈschtum/ˈshtum

(British English, informal) say nothing: I think we’d better keep schtum about this money, don’t you? OPPOSITE: open your (big) mouth Shtum is a Yiddish word from the German stumm, meaning ‘silent’.
See also: keep, schtum, shtum
Farlex Partner Idioms Dictionary
See also:
  • keep schtum
  • keep schtum/shtum
  • shtum
  • stum
  • stum [st?m]
  • keep stum
  • keep mum
  • a slanging match
  • fling (someone or something) around
  • fling around
References in periodicals archive
Therefore I have decided to stay schtum rather than provide them with yet more evidence they're working alongside a 'Philistine', as one unkindly dubbed me.
London, May 9 ( ANI ): Johnny Depp, usually is open about his off-screen life, is keeping schtum on his supposed split with French lover of 14 years Vanessa Paradis, in case their kids Lily-Rose and Jack read about it online.
* DANNII Minogue is staying schtum about rumours she could be appearing as a judge on the upcoming series of Britain's Got Talent.
Daniel Craig said he is keeping "schtum" about the plot of Bond 23, while Judi Dench bemoaned working with such an unattractive male cast.
Attempting to discuss matters of state above the din of popular music is extremely difficult, while the low-wattage lighting appears designed more for the benefit of "apple-shaped" customers trying on the latest Diamante Ruch Bandeau Dress than ministers me to keep schtum or reading complex documents on grain yields.
Yet the sites are largely keeping schtum. It could all turn out fine, but if you are a UK punter with a chunk of change lodged in the vaults of a US-centric offshore operator, perhaps it's time to consider folding, while you can.
It's been hard work keeping schtum since receiving the letter with the seal on it, which said I was being considered for an award.
The men involved are all determined to keep schtum, but as they realise that could come at a cost, the trust between them looks set to fall apart.
Folks, he hasn't even won a raffle" Ruth Davidson, the Scottish Tory leader "If he can't, sort of, keep schtum about his own views, if he can't give up the oxygen of publicity, if he can't stop setting down arbitrary red lines, then yes, he has to go" former Tory education secretary Nicky Morgan on Boris Johnson "As modern life has become ever more digitised, the loneliness of the elderly has intensified" Joanna Lumley "It was so amazing that I licked the examiner's face.
Others may genuinely believe they've only been put there by a party leader to keep schtum and vote through any bill they've proposed.
While Emirati singer Ahlam will be keeping it schtum this Ramadan - except for releasing a couple of Islamic songs - Palestinian singer Mohammed Assaf has lent his voice to a series of litanies to be released during the holy month.
Now the vast majority of businesses are keeping schtum because Cameron's all over the shop with his hokey cokey in-out strategy on the European Referendum.
But when the op is a success, Jesse decides to keep schtum and bask in the glory.
Chas agrees to keep schtum about his affair with Aaron, but it's too late.
But Clarkson, 54, has agreed to a gagging so that SCHTUM: the 100,000 fans who have bought tickets will not be disappointed.