(the running part means that is is done at a fast pace or else it would be called "walking your mouth")
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.