He ain’t right!

[Ebbtide]

He doesn’t have both oars in the water.

He’s one brick shy of a load.

His belt doesn’t go through all the loops.

He’s one sammich short of a picnic.

He ain’t playing with a full deck.

His lights are on. But no one is home.

Any more?

 

[JbirdFla]

Not the sharpest knife in the drawer
Or brightest bulb...

 

[jlauffer]

Sharp as a beachball

 

[Drop bear]

All over the place like a mad woman's shit.

 

[Danke42]

Not the sharpest spoon in the drawer.

 

[yablanowitz]

Two tacos short of a combination plate.

 

[lmleck]

Several fries short of a happy meal..

 

[jlauffer]

Couple beers short of a 6-pack

 

[knarfeng]

That fella squats with his spurs on.

"I don't know if you've noticed, but he's not operating on all thrusters, Jim."

 

[Barman1]

About as sharp as a sack of wet mice.
Foghorn Leghorn

 

[Terry M.]

Bright as a New England Fog

 

[The Amazing Virginian]

He's not the sharpest crayon in the box.

His elevator doesn't go all the way to the top.

He's got a screw loose.

The lights are on, but no one's home.

 

[rhino]

"That boy-ah's about as sharp as the point on a bowling ball."
--- Foghorn Leghorn

 

[rhino]

The elevator doesn't go all the way to the top.

The shifter works, but the gears are stripped (just made that one up).

 

[jackknife]

He's a couple rounds short of a full magazine.

 

[mqqn]

The gates are down, the lights are flashing, but the train ain't coming....

 

[Stelth]

He's as dumb as a box of rocks.

 

[Insipid Moniker]

Dumber than a sack of hammers

Couldn't spell 'cat' if you spotted him a C and a T

If I took the tail end of nothing, whittled it down to a point, hollowed it out and put his brain inside, it would rattle when you shook it.

 

[kvaughn]

If brains was gasoline, he wouldn't have enough to run a piss ants mini bike halfway around a BB.

 

[shopdoc]

Nuttier than a porta potty at a peanut festival