A phrase used to indicate that someone has revealed their true nature or a hidden aspect about themselves, often unintentionally. It can also be used when someone does something that is stereotypically associated with a group they belong to. Literally translates to 'your ID card fell out'.
Examples
- Spanish: Cuando Juan empezó a hablar de su amor por el ballet, todos le dijeron 'se te cayó el carné'.
- English: When Juan started talking about his love for ballet, everyone told him 'your ID card fell out'.