bee-brained
thick as a whale omelette
rock-dumb
thick as pig shit
dumber than a rock
retarded
dumb as dirt
dumb as a stump
dumb
shit-for-brains
dumb as a post
thick as mince
stupidass
thick as two short planks
dumber than a box of rocks
thick as a plank
dumb as a box of rocks
dumb as a doorknob
dumb as a bag of hammers
pillocky
dumb as nails
bodoh
blockheadish
stupidy
pratty
dumb as a rock
dumb like a fox
simpleminded
numbskulled
dumbassed
opaque
asinine
fucktarded
inane
fatuous
stupidish
dopey
chuckleheaded
dym
bull
numbnut
retardical
dumbbutt
one brick short of a full load
fatuitous
dumb as an ox
thick
dead from the neck up