A Spanish idiom meaning 'those who have a mouth should speak for themselves'. It's used to suggest that if someone has something to say, they should say it directly instead of sending someone else to say it for them.
Examples
- Spanish: No entiendo por qué Juan pidió a María que hablara por él, el que tiene boca no manda a callar.
- English: I don't understand why Juan asked Maria to speak for him, those who have a mouth should speak for themselves.