trash talk
noun/ˈtræʃ tɔːk/
/ˈtræʃ tɔːk/
(also trash talking)
[uncountable] (North American English, informal)- a way of talking that is intended to make somebody, especially an opponent, feel less confident
口水战（为令对手等丧失自信心）；打击对手士气的言论