Hit every branch falling out of the stupid tree
He donated his brain to science before he was done with it.
Not the brightest crayon in the box.<br />
Few crumbs short of a cookie.
Hiding behind the door when they were passing out brains.
The light is on but there is no one at home.
mad as a hatter?
His oars aren't touching the water.
he is a few fries short of a "happy meal"
Not the brightest bulb in the tanning bed?
One tortilla short of a burrito?