mouth off

verb

1. informal,  to give an opinion or speak emotionally, often without much care or consideration

Idioms and Phrases

Complain or express one's opinions loudly and indiscreetly, as in She was always mouthing off about the other members . [ Slang ; 1960s]

Speak impudently, talk back, as in He got in trouble by mouthing off to his teacher . [ Slang ; 1960s]

Example Sentences

Horseradish isn’t clamoring to burn your mouth off.

From Salon

“I don’t believe in going back to Wall Street and shooting my mouth off,” he told The Times.

From Los Angeles Times

It is a case study in the dilemma UK ministers face: they are striving to have a close and productive relationship with a White House known for shooting its mouth off.

From BBC

Vibes only count for so much, but good ones are better than the alternative – especially after the years of bad blood over Brexit, and Donald Trump's penchant for shouting his mouth off.

From BBC

The kids were mouthing off at each other in the back seat, and I began yelling at my older daughter.

From Los Angeles Times