She doesn't have all the chairs around the table.
Not the sharpest tool in the shed.
He's sharp as a thimble.
A few sandwiches short of a picnic basket.
If her IQ goes up to 40, she should sell.
About as deep as a saucer of milk.
She's not the brightest Crayola in the box!
A few fries short of a Happy Meal
He is depriving a village somewhere of its idiot.
The gates are down, the lights are flashing but the train isn't coming.
A few cards short of a full deck.
She could hold an in depth conversation with a chair.
Got a full six pack, but lacks the plastic thingy to hold them together.
A room temperature IQ.
A photographic memory, but forgot to load the film.
Bright as Alaska in December.
Fell out of the family tree.
It's hard to believe that he beat 100,000 other sperm.
Some drink from the fountain of knowledge, but he just gargled.
Takes him 1.5 hours to watch "60 Minutes"
Was left on the Tilt-A-Whirl a bit too long as a baby.
If you gave him a penny for his thoughts, you'd get change back.
He's so dense, light bends around him.
Got into the gene pool while the lifeguard wasn't watching.