go figure

Từ điển Oxford Advanced Learner 8th

go ˈfigure idiom
(NAmE, informal)used to say that you do not understand the reason for sth, or that you do not want to give an explanation for sth because you think it is obvious
• People are more aware of the risks of smoking nowadays, but more young women are smoking than ever. Go figure!
Main entry: ↑figure_idiom