talking trash

Verb

talk trash (third-person singular simple present talks trash, present participle talking trash, simple past and past participle talked trash)

1. (idiomatic, slang) To untruthfully speak of another in a belittling, deprecative, slighting manner, either in person or in absentia.

   Synonyms:

   slander, talk shit, trash-talk, assassinate, asperse, backbite, badmouth, befoul, belibel, besmirch

2. (idiomatic, slang) To speak boastfully or tauntingly about oneself in contrast with another person or other people.
   • "If there's one Celtic that tries to talk smack to me, it will be Paul (Pierce)," Kobe reported. "We're similar in age, have been through some of the same things, so he feels like he can try. But he's not as good at it as I am. I don't talk trash often, but when I do, I go for the jugular." [...]...February 6, 2013, Jackie MacMullan, article: Kobe Bryant Dishes on Celtics, ESPN online

   Synonyms:

   brag, talk smack