shoot your mouth off

US /ʃuːt jʊər maʊθ ɔːf/
UK /ʃuːt jʊər maʊθ ɔːf/
"shoot your mouth off" picture
1.

soltar la lengua, hablar de más

to talk too much, especially in a boastful or indiscreet way

:
He tends to shoot his mouth off after a few drinks.
Él tiende a soltar la lengua después de unas copas.
Don't shoot your mouth off about the surprise party.
No sueltes la lengua sobre la fiesta sorpresa.