dumber than a box of rocks
dumb as a doorknob
thick as a plank
dumb as nails
thick as two short planks
dumbnut
thick as mince
puzzlewit
boofheaded
stupidly
plank
stupidish
hammerhead
stupidass
glype
rock-dumb
thick as pig shit
dumber than a rock
shit-for-brains
fuckwit
retarded
booger brain
thick as a whale omelette
chuckleheaded
shitwit
dumb as a stump
dumb as dirt
thickwitted
dumb
dumb as a post
haramzada
moke
retardical
clod
dumbbutt
dunderheaded
thick
dumbass
jamoke
momo
bull
log
numbnut
cheesehead
beetlehead
dumb as an ox
mo
one brick short of a full load
jinnet
mislest