not very intelligent.

I could tell he was a few fries short of a Happy Meal, but unfortunately you can't arrest someone for being stupid.

Usage notes: this idiom appears in many different forms, including a few cards short of a full deck, a few bricks short of a full load, a few clowns short of a circus, and a few Cokes short of a six-pack, all with the same meaning

• the bush telegraph
• the business end
• the business end of
• the business end of something
• the calm before the storm
• the cards are stacked against
• the cards are stacked against someone
• the cart before the horse
• the casting couch
• the center of attention
• the change of life
• the chattering classes
• the child from hell
• the [child/house/mother, etc.] from hell
• the chosen few
• the coast is clear
• the cock of the walk
• the comings and goings
• the common touch
• the conventional wisdom
• the corridors of power
• the cream of the crop
• the curtain comes down on
• the curtain comes down on something
• the curtain falls