to keep on talking on a subject that is causing distress to others and provoking a fight
If you keep running your mouth, you are going to cause a big fight!
by Pino Citron January 15, 2008
talking shit, stirring shit, letting your mouth run off without thinking.
"Stop running your mouth like a bitch!"
"Dave has been running his mouth about me to everyone."
"ZOMG STFU NUBBIE DNT RUN YUR MOUF AT MEH!!1!11111"
by crazfulla October 17, 2006
saying smart ass things and generally bitching at a fast pace. Yelling out paragraphs of bitchyness really quickly. Blabbing nonsensical things in an argument just to take up time and have your voice heard.
(the running part means that is is done at a fast pace or else it would be called "walking your mouth")
"they were in a rational argument and she said something that offended him, so he started running his mouth to show his disaproval"

EX.

Him: hey, Jessica
Her: My name isn't fucking Jessica
Him: fuck, fuck, fuck, man, fuck, just fuck it man, fuck, fuck, fuck
Her: What the hell is wrong with you!?
Him: you need to stop running your mouth.
Her: Uh, I'm pretty sure it's you who is running their mouth.
by narcobitchleptic May 30, 2011
Running your mouth mean when you keep talking crap continuously.
Stop running your mouth before you start a fight idiot.
by Aestheticxlly_0 October 19, 2018
When you and/or someone else excessively insult or talk bad about someone something, even when directed to stop. usually, the bully keeps this up to the point where the person directed to the verbal assault becomes angry, irritated, or distressed. See talking smack, talking shit talking bad, verbal bullying, back talk
"Dude, stop running your mouth, your only going to piss them off even more!'
by Suburbanz71 November 8, 2017