be (as) thick as a short plank

be (as) thick as a short plank

To be remarkably stupid, dimwitted, or obtuse. I smoked a lot of marijuana when I was in high school, so I was as thick as a short plank by the time I finally graduated. Jen's new girlfriend is very nice, but she's thick as a short plank.

See also: plank, short, thick

Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.