Doesn’t know whether to scratch his watch or wind his butt
A few fuses short of a full circuit
A tire short of an eighteen wheeler
Doesn’t have all the chairs at the table
Dumber than a bag of rocks
A few pecans short of a fruitcake
If you gave him a penny for thoughts, you’d get change
Dumb as a salt shaker
Has a mind like a steel trap: rusty and illegal in most states
Knitting with only one needle
Too much chlorine in the gene pool
Not the quickest bunny in the forest
The hard drive is spinning but the OS hasn’t been installed
Not running on all thrusters
A few toppings short of a Deluxe Pizza
A few burgers short of a barbecue
A few roos loose in the top paddock
The wind is blowing but nothing is moving
A few colors short of a rainbow
A few boats short of a fleet
A few noodles short of a chow mein
A few bristles short of a broom
Hasn’t seen the ball since kickoff
A few players short of a team
Couldn’t hit the floor if he fell on it
A few sheep short of a flock
A few gunmen short of a posse
Not the quickest horse in the stable
The umbrella is up but there’s no rain