“Let the cat out of the bag”in other languages

Same idea, different pictures

English has two, and both come with stories that can't be proven. The cat is said to come from market tricks, a cat sold in a bag as a piglet; the beans from Greek voting with beans. Japanese simply says the mouth slipped, kuchi ga suberu.

French sells the fuse, vendre la mèche, the fuse of an explosive charge in siege warfare. Give it away to the enemy and the whole plan blows up.