opaque
thick
one brick short of a full load
dumbbutt
bull
dumb as an ox
retardical
numbnut
simpleminded
numbskulled
dumbassed
dunderheaded
dumbass
bubbleheaded
dopey
muddlebrained
pratty
dumb as a bag of hammers
lamebrained
stupidy
thick as mince
blockheadish
bodoh
dumb as nails
stupidass
stupidish
sill
goofball
dumb as a post
dumb as dirt
rock-dumb
thick as a whale omelette
thick as pig shit
dumb
dumb as a stump
dumber than a rock
baka
retarded
boofheaded
shit-for-brains
dumbish
twp
goosish
fool
soft
dumber than a box of rocks
derpy
dumb as a box of rocks
thick as two short planks
thick as a plank