劈腿只为秀贞操
[pī tuĭ zhĭ wéi xiù zhēn cāo]
Literal translation would be 'cheating just to show chastity'. It appears ironic; usually these words don’t go together so there's an underlying meaning that might express a cynical view toward purity displays that aren’t genuine or social media flaunting behavior meant to gain public recognition of one's faithfulness when actually committing infidelity.