对你微笑纯属礼貌对你微笑把酒干掉
[duì nĭ wēi xiào chún shŭ lĭ mào duì nĭ wēi xiào bă jiŭ gān diào]
Splitting this into two phrases 'Smiling at you only out of politeness' and 'Smiling at you while finishing a drink', it describes the situation of pretending or faking a smile either because of politeness or during a moment where drinks are consumed.