Good idea Cleo.. saves alot of typing...
Calling him stupid would be an insult to stupid people.
Calling him a pea brain would be an undeserved compliment.
Can be outwitted by a jar of Marshmallow Fluff.
Can't find his ass with two hands and a periscope/ compass/flashlight/bloodhound (in a locked closet).
Car's only got three wheels, and one's going flat.
Carries a tire gauge in him purse.
Cauliflower for brains.
Charming as a carbuncle.
Cheezwiz for brains.
Chimney's clogged.
Clock doesn't have all its numbers.
Collects cards for Craig.
Consumes hard drugs as vitamins.
Contributes to the population problem.
Couldn't organize a piss-up in a brewery.
(Common in Australia.) Couldn't pour water out of a boot with instructions on the heel.
Couldn't think his way out of a paper bag.
CPU not connected to the bus.
Cranial cavity filled with neutronic matter.
Cranio-rectally inverted.
Cursor's flashing but thime's no response.
Defective hard drive / boot sector.
Diarrhea of the mouth; constipation of the ideas.
Does aerobics... in his head.
Does everything the hard way, like making love standing up in a hammock.
Doesn't have all his cornflakes in one box.
Doesn't have all his dogs on one leash / cups in the cupboard / groceries in the same bag.
Doesn't have all the dots on his dice / pens in him plotter.
Doesn't have both oars in the water.
Doesn't have his belt through all the loops.
Doesn't have the sense God gave an animal cracker.
Doesn't have two neurons to rub togethim.
Doesn't just know nothing; doesn't even suspect much.
Doesn't know much, but leads the league in nostril hair.
Doesn't know which side the toast is buttered on.
Doesn't quite sample at the Nyquist rate.
Donated him body to science... before he was done using it.
Downhill skiing in Iowa.
Driving with two wheels in the sand.
Dropped his second stage too soon.
Dumb as asphalt / a stump / a sack of hammers.
Dumber than a chicken / box of hair/rocks.
Easier to count the bricks left than the bricks missing.
Echoes between the ears.
Eight pawns short of a gambit.
Elevator doesn't go all the way to the top floor / penthouse.
Elevator goes all the way to the top but the door doesn't open.
End of season sale at the cerebral department.
Fighting the war with a starter pistol / water pistol / pop gun / cap gun.
Finds a flat by swapping tires.
Finds canonical humor collections amusing.
Fired from McDonald's for having a short attention span.
Fired him retro-rockets a little late.
Flaky.
Flying/landing on one engine.
Folds ace plus red jack hand when playing blackjack.
Forgot to pay his brain bill.
Four cents short of a nickel.
Fruity as a nutcake.
Full throttle, dry tank.
Gasoline engine, diesel fuel.
Gates are down, the lights are flashing, but the train isn't coming.
Gavel doesn't quite hit the bench.
Gets hypnotized on the despun section.
Goalie for the dart team.
Got a life, but wasn't sure what to do with it.
Guillotining him would make only an aesthetic difference.
Gyros are loose.
Had a head crash.
Half a bubble off plumb.
Hard to tell if he has an ace up his sleeve or if the ace is missing from his deck altogethim.
Has a few wait states.
Has a full six-pack but lacks the plastic thing to hold them togethim.
Has a leak in his ceiling.
Has a one-way ticket on the Disoriented Express.
Has a slow clock.
Has all him bricks, but no cement holding them togethim.
Has all the brains God gave a duck's ass.
Has an IQ of 2, and it takes 3 to grunt.
Has his solar panels aimed at the moon.
Has it floored in neutral.
Has no discretionary intellect.
Has no upper stage.
Has only one chopstick in the chowmein.
Has signs on both ears saying "Space for Rent".
Has so few thoughts that when he free associates, it's like watching tennis.
Has the attention span of an overripe grapefruit.
Has the brains of a house plant.
Has the Grand Canyon under the crew cut.
Has the IQ of a salad bar / ice cube.
Has the mental agility of a soap dish.
Has two brains; one is lost and the othim is out looking for it.
Hasn't got all his china in the cupboard.
Hasn't got the brains God gave a cat.
Having a party in his head, but no one else is invited.
DD