心如柠檬天然酸心如柠檬天然凉
[xīn rú níng méng tiān rán suān xīn rú níng méng tiān rán liáng]
'Heart is as tart and naturally cool as lemon'. Used metaphorically to convey one has a sour or bitter feeling yet remains calm and collected, reflecting a somewhat jaded outlook on life, often related to matters of the heart.