dimwit
stun
subnormal
not the sharpest tool in the box
not the sharpest tool in the shed
not the sharpest knife in the drawer
halfwit
dirtbrain
idiot
stupidass
stupid
subintellectual
divvie
half-wit
changeling
cretin
moron
imbecile
retard
birdbrain
simpleton
dipshidiot
simple
mentally challenged
half-witted
fool
submoron
drool bucket
idiot savant
gormless
sophomania
nonintellectual
unintelligent
underbrained
lackbrain
lunkhead
hammerhead
dunce
shithead
fuckhead
bonehead
knucklehead
dumbass
loggerhead
blockhead
muttonhead
numskull
dunderhead
half-brained
fuckwad
weak
unintelligence
dumb genius
intellectually challenged
room-temperature IQ
cerebrally challenged
subnormality
lackluster
dysrationalia
incompetent
dropkick
debutard
underwitted
rube
muggle
wet end
light-witted
monkey
pseudointellectual
subexpert
technotard
dipstick
sad sack
dense
mentally retarded
IQer
nonintelligence
deficient
hayseed
yahoo
maladroit
chawbacon
hick
genia
nonexpert
yokel
bumpkin
amateur
clown shoe
gimboid
vacancy
artificial stupidity
innumerate
muppet
indocible