高调的学霸低调的学渣
[gāo diào de xué bà dī diào de xué zhā]
This translates to 'showy top student, modestly acting poor student'. It might imply someone is smart enough but pretends not to be, possibly to blend in with the crowd. It can also indicate different personas for different audiences; being high profile when showcasing strengths and low key when exposing weaknesses.