short bus
dim-bulb
lunky
one fry short of a Happy Meal
dunny
lead-footed
peabrain
Boeotian
thick as a brick
beefheaded
thickheaded
heavy
swear
dym
loggerheaded
blunt-witted
fuckheaded
lameoid
lamebrained
boofheaded
thickwitted
dumb as nails
dottle
thick-skulled
muddlebrained
tardy
frontal lobeless
dumb like a fox
autistic
wooden-headed
dilatory
clodpated
slowsome
boobyish
sweer
midget-minded
drowsy
blonde
dull-minded
poky
nonsmart
sleepy
dumb as a doornail
cerebrally challenged
goofy ahh
fatuitous
intellectually challenged
plumbeous
bovine
weak-minded