He's a few bricks shy of a load

Meaning

This means someone is lacking common sense or intelligence. It evokes the image of a delivery truck that did not get filled all the way up.

Dismissive, folksy

Used in a sentence

• I would not trust him to run the shop, he is a few bricks shy of a load.
• He tried to pay his taxes with store coupons, bless him, he is a few bricks shy of a load.
• That guy is definitely a few bricks shy of a load.