yellow dog 不参加或不协助工会的工人，卑鄙的人

【例句】
I dislike Tom for he is a yellow dog.
我讨厌汤姆，他是个卑鄙小人。

He is a yellow dog, and nobody would like to get along with him.
他是个卑鄙小人，没人喜欢和他一起。