我不是柠檬为谁心酸
[wŏ bù shì níng méng wéi shéi xīn suān]
'I'm not a lemon, but for whom do I feel bitter?' This interesting idiom might imply that although lemons naturally taste sour (representing negativity), why does the user feel bitter about something/someone which is supposed to bring joy, reflecting confusion or conflicted emotions.