(as) thick as two short planks
US /əz θɪk əz tuː ʃɔrt plæŋks/
UK /əz θɪk əz tuː ʃɔrt plæŋks/
1.
very stupid
:
•
He's (as) thick as two short planks, he never understands anything.
•
You'd have to be as thick as two short planks to believe that story.