stuuupid
stupidish
dumb like a fox
simpleminded
derpy
numbskulled
dumbassed
fatuitous
muddlebrained
dumbass
dunderheaded
pratty
blockheadish
lamebrained
stupidy
cockamamy
bodoh
anserine
airheaded
tomfool
daft
baka
numbnut
dumbbutt
dumb as an ox
thick
bull
one brick short of a full load
retardical
thick as a plank
dumbish
dumber than a box of rocks
thick as two short planks
stupidass
dopey
dumb as a doorknob
dumb as a box of rocks
sawney
goosish
twp
tardish
soft
fool
thick as mince
peabrained
ninnyish
doinky
tomfoolish
dumb as nails
lackwitted