想念突然性敷衍的那张脸
[xiăng niàn tū rán xìng fū yăn de nèi zhāng liăn]
Translated as 'missing that suddenly indifferent expression'. It reflects on remembering or longing for the moment where someone had a brief and casual (almost apathetic) facial expression. There might be underlying significance attached to why this particular reaction or appearance during interactions has left an impact.