a few bricks shy of a load
A fool who thinks they can count, but they can’t even count to three without crying.
He tried to count bricks. He counted to one, then screamed. He’s a few bricks shy of a load.
She said a load was just one brick. She’s a few bricks shy of a load.
He tried to add two bricks and got confused. He’s a few bricks shy of a load.