(as) thick as two short planks

(as) thick as two short planks

Remarkably stupid, dimwitted, or obtuse. I smoked a lot of marijuana when I was in high school, so I turned out thick as two short planks by the time I finally graduated. Jen's new girlfriend is very nice, but she's as thick as two short planks.
See also: plank, short, thick, two
Farlex Dictionary of Idioms.

(as) thick as two short ˈplanks

(informal) (also (as) thick as ˈshit taboo, slang) (British English) (of a person) very stupid: Because she’s a model, people assume she’s as thick as two short planks, but she isn’t. OPPOSITE: (as) bright as a button
Thick is the opposite of thin and can also mean ‘stupid’ in informal language.
See also: plank, short, thick, two
Farlex Partner Idioms Dictionary
See also:
  • thick as two short planks
  • (as) thick as two planks
  • thick as two planks
  • be (as) thick as a short plank
  • (as) thick as a brick
  • be (as) thick as a brick