idiot
dirtbrain
subnormal
stun
mentally challenged
halfwit
half-witted
dimwit
fool
stupidass
birdbrain
divvie
peon
half-brained
subintellectual
submoron
drool bucket
not the sharpest tool in the box
unintelligence
not the sharpest knife in the drawer
simple
simpleton
not the sharpest tool in the shed
cerebrally challenged
intellectually challenged
dumb genius
lackbrain
nonintellectual
dipshidiot
subexpert
subnormality
underbrained
half-wit
moron
cretin
unbright
stupid
imbecile
retard
changeling
unintelligent
fuckwad
nondescript
simple-mindedly
vacancy
dense
muggle
monkey
gobemouche
gobe-mouche