A few beads short in her rosary.
A few too many lights out in his Christmas tree.
A few french fries short of a Happy Meal.
A room temperature IQ.
A walking argument for birth control.
Batteries not included.
Elevator doesn't go all the way to the penthouse.
Elevator goes all the way to the top but the door doesn't open.
Four cents short of a nickel.
Got into the gene pool while the lifeguard wasn't watching.
He's so dense, light bends around him.
His head whistles in a crosswind.
His mind wandered and never came back.
If he were any more stupid, he'd have to be watered twice a week.
If you stand close enough to him, you can hear the ocean.
It's hard to believe he beat 100,000 other sperm.
Knitting with only one needle.
Living proof that nature does not abhor a vacuum.
Plays solitaire for cash.
Receiver is off the hook.
So dumb, blondes tell jokes about him.
Takes her two hours to watch 60 Minutes.
The cheese slid off his cracker.
Uses his head to keep the rain out of his neck.