(as) thick as two short planks
US /əz θɪk əz tuː ʃɔrt plæŋks/
UK /əz θɪk əz tuː ʃɔrt plæŋks/

1.
dumm wie Bohnenstroh, strohdumm
very stupid
:
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He's (as) thick as two short planks, he never understands anything.
Er ist dumm wie Bohnenstroh, er versteht nie etwas.
•
You'd have to be as thick as two short planks to believe that story.
Man müsste dumm wie Bohnenstroh sein, um diese Geschichte zu glauben.