又想当婊子又想立牌坊

yòu xiǎng dāng biǎo zi yòu xiǎng lì pái fāngyouxiangdangbiaoziyouxianglipaifang

1. lit. to lead the life of a whore but still want a monument put up to one's chastity (idiom)
2. fig. to have bad intentions but still want a good reputation
3. to want to have one's cake and eat it too

Study it in Yanamino