有一种监狱叫学校有一种囚犯叫学生
[yŏu yī zhŏng jiān yù jiào xué xiào yŏu yī zhŏng qiú fàn jiào xué shēng]
Expressing dissatisfaction or criticism towards the education system by comparing it to prison. The idea suggests students feel restricted or oppressed, unable to enjoy freedom.