rat on someone/something
phrasal verb with rat verb slang disapproving uk/ræt/ us/ræt/
背叛;（尤指）告密出卖，对…背信弃义
to not be loyal to someone, especially by giving away secret information about them, or to fail to do something that you said you would do
He ratted on us. 他出卖了我们。
They ratted on the deal. 他们不守信用，谈好的交易出尔反尔。