谁的笑颜不是别人的梦魇
[shéi de xiào yán bù shì bié rén de mèng yăn]
Translated as 'Whose smile is not another's nightmare', it reflects a philosophical thought or a feeling where happiness or success (represented by smiles) may be the result or cost of someone else's suffering, hinting at social issues, jealousy, or irony.