dog in the manger 直观看就是占马槽的狗，是指占着茅坑不拉屎；损人不利己，用来比喻那些占着位置不干活的人。

【例句】
Don't be such a dog in the manger ! If you don't want that model plane, give it to Tony.
不要占着茅坑不拉屎！如果你不玩那架模型飞机，就送给托尼吧。

I'd better quit now. I don't want to be a dog in the manger.
我最好现在离职。我不想占着茅坑不拉屎。