Euphemisms for Crazy or Lacking Brainpower

[Camazotz Automat]

I never tire of reading She's not playing with a full deck or His pilot light is out.

I'd like to read about one hundred more.

[jazmunda]

The saying we use Down Under is "He's a few snags short of a barbie".

Snags being slang for sausages and barbie being short for BBQ.

It's our version of "He's a few sandwiches short of a picnic".

[Heather Wade]

This guy is loopy.
Crazy as a barrel of shaved cats.
One beer shy of a picnic (Trailer Park Boys, I think)
All sixes and sevens.

I'll think of more.  Right now I'm about as tired as a one-legged man that just finished a marathon.

[Yorkshire pud]

mad as a box of frogs.
Not the sharpest knife in the drawer

[Nick el Ass]

I always giggle when I hear someone say something about someone being dumber than a bag of hammers, or that guy/gal isn't the brightest crayon in the box. My personal favorites is the cheese has fallen of his/her cracker.

[Heather Wade]

(!) Sharp as a bowling ball.
Dumb as a box of rocks, yeah I love that one.

[aldousburbank]

We use this among my tribe:
He's a few poles shy of a full tipi.

[Eddie Coyle]

    "That kid is fuckin' gonzo".

     "I think he/she got hit by a bus". *Common South Boston phrase, due to the oft insistence that said whacko had started life normal but was hit by a bus in their youth, causing the resultant idiocy.

     ** Despite this term being utilized frequently, only one of these nuts was ACTUALLY hit by a bus.

     *** And that was "Johnny Fire Radio", circa 1960. His moniker being based on his carrying a walkie talkie w/o batteries and waiting on a wall**** near the fire station and chasing the trucks when they went out for a call. 

    **** Yes, Johnny was one of the "wall-nuts", a collection of loons and Albanian emigres.

[Juan]

He ain't right.

[SaucyRossy]

He almost killed himself eating a pizza roll.

[Nick el Ass]

That man/woman is a few french fries short of a happy meal.

[lonevoice]

For lacking in brain power, here are two that I like:

1.  The wheel's still turning, but the hamster's dead
2.  He's so dumb, the government uses his head for wind tunnel testing

For crazy, I like this one:

[phrodo]

Not the sharpest tool in the shed
A few cards shy of a full deck
Not playing with a full deck
Short bus rider
Bat shit crazy
looney tunes
his porch light's on but nobody's home
if he had a brain he'd take it out and play with it
if brains were dynamite he wouldn't have enough to blow his nose.
has an IQ below room temperature

just a few of my favorites . 

[gbneely]

He lacks the intellectual horsepower...

Nuttier than squirrel turds.

[yumyumtree]

Geranium in the cranium is from Dear Abby or Ann Landers many decades ago.

[Catsmile]

Dokyun (DQN):
Means “idiot”. Not just any idiot though, but someone so stupid that when they do something stupid, they actually think they are doing something clever.

"Dokyun-ya!” (ドキュンや!) In Japanese, “-ya!” tacked at the end of a noun or adjective can sometimes be interpreted as ” Jeez, what a ____"

Baka:
Means "idiot", "stupid", "absurd", or (as an adjectival noun) "foolish"

[ACE of CLUBS]

If he had two brain's ...... he'd be a half wit.

He's ninety cents short of a buck .....

The lights are on ..... but, nobody's home ....

[Heather Wade]

"Fruity as a nutcake," -Captain Kirk

[RealCool Daddio]

Stunned as a bag of hammers.

[wr250]

he nooryed that good.

[ManiacMatt]

He's a taco short of a combination plate.

He's a couple of bricks shy of a load.

That guy is a real goober.

He's a noory.

What a noory!

He pulled a Noory.

[=Schlyder=]

Liberal.

[eyenoeyeno]

Not the brightest crayon in the box

A few planets short of a federation  (yes, I'm talking to you)

all foam no beer

got a kink in their slinky

Butter slipped off the pancake

One bubble short of a bath

Panties in a twist (specifically for crazy bitches)

[Camazotz Automat]

I greatly underestimated how much I would love this thread.

It's easy enough to do a search on such a topic, but would much rather hear from/through the filter composed of fellow Bellgabbers.

My thanks to all so far and to those forthcoming.

[b_dubb]

Falkie

[PB the Deplorable]

He's got a head on him like a burnt match

[PB the Deplorable]

Shit for brains

[aldousburbank]

Fumblefuck

[GeorgieForPresident2216]

Coast Insider.

[GeorgieForPresident2216]

The lights are on but no one's home.
Not the brightest bulb in the box.
Dumb as a sack of potatoes. (I may have just invented that one)