dumben
dumb
dumbfounder
dumbify
dumb like a fox
stare like a stuck pig
duncify
dunderheaded
dumbass
stupidish
dumb as nails
stuuupid
muddlebrained
lamebrained
beclown
blockhead
dumb as a rock
numbskulled
simpleminded
dumbassed
stupidly
thickhead
dumbbutt
numbnut
thick
bull
one brick short of a full load
dumb as an ox
stonker
retardical
thick as a plank
dumb as a box of rocks
dumb as a doorknob
thick as two short planks
dumbish
tomfool
dumber than a box of rocks
dym
thickwit
tardface
baka
dumb cluck
stupidity
bubblehead
gristlehead
smooth brain
ass
dumbarse
dumbski
swoose