And I'm sure the list will just grow & grow

Sir Gabble of Ratchet




Your mental elevator doesn't go to the top floor.

I don't think you are playing with a full deck.

You don't have both oars in the water.

Your lights are on, but nobody's home.

When you fell out of the stupid tree, you must have hit every branch on the way down.

If brains were bird droppings, you would have a really clean cage.

You are a few clowns short of a circus.

Hey, with a couple more fries, you could be a Happy Meal.

You must be the result of a top secret experiment in Artificial Stupidity.

You are two beers shy of a six-pack.

You're dumber than a box of hair.

With a few points added to your IQ, you could be a clam.

If you kept your brains in your butt, you'd have room to be more than a moron.

You do not have all your corn flakes in one box

Your casserole is missing a few peas.

Your wheel is spinning, but the hamster's dead.

Your cheese has slid off your cracker.

Your cap has been snaffled.

Your body may be by Fisher, but your mind is by Mattel.

You have an IQ of 2, but it takes 3 to grunt.

Your intellect is rivaled by garden tools.

You are not the sharpest knife in the drawer.

You are about as smart as bait.

Did you forget to pay your brain bill?

I think your sewing machine has run out of thread.

Your antenna doesn't pick up all the channels.

Your belt doesn't go through all the loops.

You're proof that evolution CAN be reversed.

Your receiver is off the hook.

Your skylight has a leak.

Your slinky is kinked.

You've got too much yardage between your goal posts.

You're a .22-caliber intellect in a .357 Magnum world.

You're doomed to be a pacifist in the battle of wits.

You may have a photographic memory, but your lens cover is Super Glued on your camera.

You are a prime candidate for natural de-selection.

You're a steering wheel short of a Yugo.

Your Titanic intellect is in an ocean filled with icebergs.

Your teapot lid is cracked.

You are windup clock without a key.

You're almost half smart.

Don't think too much, or you'll void your warranty.

Say, you've really sharpened your sleeping skills.

Your batteries weren't included.

You were born a day late, and nothing's changed.

You must have evolved from the shallow end of the gene pool.

You were born stupid and built to last.

You're broadcasting static.

If brains were dynamite, you wouldn't have enough to blow your nose

Not quite the same but

" Act your age not your shoe size"

How about:

You're not the brightest crayon in the box.
When God was passing out brains, you thought he said trains.

And my favorite (but of couse the person you are saying this to will NOT get it):

I refuse to have the battle of wits with someone who is unarmed.



Cat

I love these, Gabble!

My mom always said:  "He's eight cents short of a dime.".  ( A dime is worth ten cents for our overseas friends.  ;) )

A few ants short of a picnic.

As dumb as an ox.

As dumb as a brick.

A few cards shy of a deck.

Not the brightest bulb on the string.

*My personal favorite*

"You're about nine kinds of stupid, arent' you?"




Where've ya been lately?  :-/  

The most comman one I say is

He is about as useful as an ashtray on a motorbike.

I think a few of these lines are a bit too old and cliche to be really good, but "box of hair" = comedy gold.

"Your about as pointless as a rubber ball"  ;D

I always liked "You're one taco short of a combination plate."  ;D

How about "dumber than a box of rocks"

One of my favourites from a list I was emailed was "since our last meeting this employee has hit rock bottom and carried on digging" I must see if I've still got that email as I recall it was all pretty good.
One i thought up all by myself was 'not the brightest button in the tin'

A friend of mine uses this one a lot: "You're about as much use as a chocolate fireguard"