let the cat out of the bag englannista kaikille kielille

Kieli	Käännökset
espanja	irse de la lengua, tirar de la manta
norja	slippe katta ut av sekken
puola	wypuścić kota z worka
ranska	vendre la mèche, cracher le morceau
saksa	die Katze aus dem Sack lassen
tšekki	prořeknout se, vybreptat to
venäjä	вынести сор из избы (vynesti sor iz izby)

(idiomatic) To disclose a secret; to let a secret be known, often inadvertently.

He proved himself as decent, decorous, and conscientious as Peter was rampant, boisterous, and — This last epithet I choose to suppress, because it would let the cat out of the bag.
It was going to be a surprise party until someone let the cat out of the bag.

Sanakirja.org