Every single person is a fool, insane, a failure, or a bad person to at least ten people.
— Mokokoma Mokhonoana
airhead
aphorism
aphorisms
aphorist
aphorists
around-the-bend
ass
bad
bad-people
bad-person
bananas
batty
birdbrain
blockhead
bonkers
boob
bozo
brainless
buggy
bushed
certifiable
chowderhead
chowderheaded
chump
clod
coot
crack-brained
cracked
crackers
crackpot
crazed
crazy
cretin
cuckoo
daft
dead-loss
demented
deranged
dim
dimwit
dimwitted
dingbat
dipstick
disappointment
disturbed
ditz
dolt
donkey
dope
dork
dud
dullard
dumb
dumb-ass
dumb-cluck
dumbhead
dumbo
dumdum
dummy
dunce
dunderhead
fail
failure
fathead
flake
fool
foolhardy
foolish
funny
galoot
goat
goober
goof
goofball
goofus
goon
half-baked
halfwit
halfwitted
harebrained
hilarious
humor
humorous
humour
idiot
idiotic
ignoramus
ill-advised
ill-considered
imbecile
impolitic
imprudent
incautious
informal-no-hoper
injudicious
insane
insanity
jerk
joke
jokes
jughead
klutz
lamebrain
loco
loony
loopy
loser
lummox
mad
mad-as-a-hatter
meatball
mentally-disordered
mentally-ill
mindless
moron
nerd
nincompoop
ninny
nitwit
non-compos-mentis
not-all-there
numbnuts
numbskull
nuts
of-unsound-mind
pea-brained
peabrain
psycho
psychotic
putz
quotations
quotes
rash
reckless
sap
satire
schizophrenic
schlemiel
schlep
schmuck
screwy
silly
simpleton
stark-raving-mad
stupid
thick
thickhead
thoughtless
turkey
twerp
twit
unbalanced
underachiever
unhinged
unintelligent
unstable
unwise
wacko
witless
wooden-headed
write-off
zombie