Meaning
To spill the beans / To let the cat out of the bag
Example
Pedi para não contar nada, mas ela deu com a língua nos dentes e todo mundo ficou sabendo.
I asked her not to say anything, but she spilled the beans and everyone found out.
Origin
The image is of someone so excited they bite their own tongue by accident while talking — revealing a secret.
Practice idioms with the Idiom Trainer
Falando's Idiom Trainer teaches you to recognize idiom meanings and create sentences using them, so you can speak like a Brazilian.
More idioms
Acertar na moscaTo guess correctly / To hit the nail on the headAmigo da onçaA fake/false friendAndar na linhaTo toe the line / To behave properlyArmar um barracoTo cause a public sceneRodar a baianaTo cause a public scene / To go ballisticArrumar sarna pra se coçarTo ask for troubleArrastar as asasTo hit on someone / To flirtAbrir o jogoTo come clean / To open upArregaçar as mangasTo roll up one's sleeves / To get to workAgarrar com unhas e dentesTo hold on for dear life / To seize an opportunity