你姐姐独一无二你姐夫独一有二
[nĭ jiĕ jiĕ dú yī wú èr nĭ jiĕ fū dú yī yŏu èr]
Translates to 'Your sister is one of a kind; your brother-in-law is unique in twos'. It humorously emphasizes uniqueness, perhaps referring positively (one-of-a-kind traits) but with a hint of irony (suggesting brother-in-law isn’t quite so exceptional).