"Wolf's heart and dog's lungs" is a derogatory idiom. Its literal meaning is "a wolf's heart and a dog's lungs," and it is used as a metaphor for a person who is vicious, ungrateful, and utterly devoid of humanity. In traditional culture, wolves and dogs are often regarded as symbols of cruelty, greed, and baseness, so using their organs to refer to a person's character emphasizes cold-bloodedness and treachery. The idiom comes from Feng Menglong's *Stories to Awaken the World* from the Ming Dynasty, and it is widely used in folk speech and literary works, often to condemn those who return kindness with enmity, forget righteousness in the face of profit, or harm others. It is mostly used in severe criticism or angry accusations, with extremely strong emotional coloring, expressing the speaker's intense indignation and contempt for someone's moral degeneration. It should be noted that this idiom has a very strong tone and is generally used to reprimand serious and vile behavior, so it is not suitable for casual use in light or formal occasions.
📝 Example
1. He actually framed his own brother in order to fight over the family estate—what a wolf-hearted, dog-lunged person. (Describing someone cruel and utterly devoid of family feeling.)
2. When you were in trouble back then, I gave you all the help I could, and now you turn around and bite me—you are truly wolf-hearted and dog-lunged! (Describing someone ungrateful and returning kindness with enmity.)