a brick short of a load

be one brick short of a (full) load

To be not very intelligent or of questionable mental capacity. This expression can appear in many different forms and variations (e.g., "a few sandwiches short of a picnic," "one card shy of a full deck," etc.). He says he's going to start a business selling bees as pets—I think he may be one brick short of a load. The new manager is nice enough, but he's one brick short of a full load, if you ask me.
See also: brick, load, of, one, short
Farlex Dictionary of Idioms.

a brick short of a load

or

one brick short of a load

If you say that someone is a brick short of a load or one brick short of a load, you mean that they are stupid or crazy. He doesn't seem scared about the fight, but then he is a brick short of a load. She was rushing around, one brick short of a load, upsetting everyone.
See also: brick, load, of, short
Collins COBUILD Idioms Dictionary, 3rd ed.

a brick short of a load

(of a person) stupid. informal
This is one of a number of humorous variations on the theme of someone not possessing their proper share of brains or intelligence; compare, for example, with a sandwich short of a picnic (at sandwich).
See also: brick, load, of, short
Farlex Partner Idioms Dictionary
See also:
  • be one brick short of a (full) load
  • be one card short of a full deck
  • be one card shy of a (full) deck
  • be several bricks short of a (full) load
  • be several cards short of a (full) deck
  • be several cards short of a full deck
  • be one sandwich short of a picnic
  • two bricks shy of a (full) load
  • a few cards short of a (full) deck
  • a few cards shy of a (full) deck