(as) thick as two short planks

US /əz θɪk əz tuː ʃɔrt plæŋks/
UK /əz θɪk əz tuː ʃɔrt plæŋks/
"(as) thick as two short planks" picture
1.

笨得要命, 愚蠢至極

very stupid

:
He's (as) thick as two short planks, he never understands anything.
笨得要命,什麼都聽不懂。
You'd have to be as thick as two short planks to believe that story.
你得笨到家了才會相信那個故事。