柠檬加醋心更酸薄荷加冰心更冷
[níng méng jiā cù xīn gèng suān bó hé jiā bīng xīn gèng lĕng]
Meaning 'Lemon with vinegar makes the heart even more bitter, mint with ice makes the heart even colder'. The metaphor uses lemon and vinegar for sourness and bitterness, and mint and ice for coldness. It reflects feelings of jealousy, loneliness, or despair.