No one's going to say he's the sharpest knife in the drawer.
Sam Adam, Jr., arguing to the jury in United States v. Rod Blagojevich.
Not the brightest light on the porch.
One beer short of a six-pack.
Two bricks shy of a load.
A few fries short of a Happy Meal.
One twist short of a slinky.
The gates are down, and the lights are flashing, but the train isn't coming.