老师比卫生纸都能扯
[lăo shī bĭ wèi shēng zhĭ dōu néng chĕ]
'Laoshi Bi Weishengzhi Dud Neng Che', roughly translating into 'Teacher can talk endlessly like toilet paper'. It is a humorous statement that depicts someone very eloquent or talks a lot non-stop without substance similar to a never-ending roll of toilet paper.