He's a pork pie short of a picnic.
A few fries short of a happy meal.
A few beers short of a six pack.
A few peas short of a casserole.
The wheel's spinning, but the hamster's dead.
One fruit loop shy of a full bowl.
One taco short of a combination plate.
A few feathers short of a whole duck.
All foam, no beer.
The cheese slid off his cracker.
Body by Fisher, brains by Mattel.
Has an IQ of 2, but it takes 3 to grunt.
Warning: Objects in mirror are dumber than they appear.
Couldn't pour water out of a boot with instructions on the heel.
He fell out of the stupid tree and hit every branch on the way down.
An intellect rivaled only by garden tools.
As smart as bait.
Doesn't have all his dogs on one leash.
Elevator doesn't go all the way to the top floor.
Forgot to pay his brain bill.
Her sewing machine's out of thread.
His antenna doesn't pick up all the channels.
His belt doesn't go through all the loops.
Proof that evolution CAN go in reverse.
Receiver is off the hook.
Several nuts short of a full pouch.
Skylight leaks a little.
Too much yardage between the goal posts.
In the pinball game of life, his flippers were a little further apart than most.
A few clowns short of a circus.
His elevator doesn't reach the top floor
He checked out of Hotel Brainy years ago
She's a result shot of a classified round up
She's one tit short of an udder
If he was any more stupid he would photosynthesise in sunlight
He's ten pence short of a pound
She's a dolly mixture short of a quarter
Thicker than a donkey's dangler
He's got a rip in his marbles bag
She's got a tile loose
She hasn't got both hands on the steering wheel
When you look in his eyes you can see that there is no one driving
She's stepped off of the pavement
Lights on, door open, no one at home
Trying to explain something to him is like trying to give a fish a bath
He'll be doing joined up writing next
He's wired up to the moon
She's like the Venus de Milo, very pretty but not all there
He doesn't know the meaning of the word fear, in fact, he doesn't know the meaning of a lot of words
He's one putt short of a par