柠檬吃醋心该有多酸
[níng méng chī cù xīn gāi yŏu duō suān]
Refers to experiencing jealousy that is so strong it feels like eating lemon; emphasizing a feeling of intense envy or resentment towards another party involved in one's own matters or relationships, especially concerning love. It humorously depicts how jealousy makes one feel very sour or bitter inside.