揣着明白装糊涂揣著明白裝糊塗 1.to pretend to not know2.to play dumb
放着明白装糊涂放著明白裝糊塗 to pretend not to know (idiom)
聪明一世，糊涂一时聰明一世，糊塗一時, (idiom) even the wisest can have a momentary lapse in judgment; every man has a fool in his sleeve
烂泥糊不上墙爛泥糊不上牆 see 烂泥扶不上墙[làn ní fú bù shàng qiáng]
(old) to seal an examinee's name on the examination paper to prevent fraud