Lets face it, there are a lot of dumb people out there. Sometimes you want to express how stupid they really are and here's how,

An intellect rivaled only by garden tools.
As smart as bait.
Doesn't have all his dogs on one leash.
Doesn't know much, but leads the league in nostril hair.
Elevator doesn't go all the way to the top floor.
Forgot to pay his brain bill.
His belt doesn't go through all the loops.
If he had another brain, it would be lonely.
Missing a few buttons on his remote control.
Proof that evolution CAN go in reverse.
Receiver is off the hook.
Surfing in Nebraska.
An experiment in Artificial Stupidity.
A few beers short of a six-pack.
A few peas short of a casserole.
The cheese slid off his cracker.
Warning: Objects in mirror are dumber than they appear.
Couldn't pour piss out of a boot with instructions on the heel.
He fell out of the stupid tree and hit every branch on the way down.
Not the sharpest knife in the drawer.