few bricks short of a load

few bricks short of a load

 and few cards shy of a full deck; few cards short of a deck; not playing with a full deck; two bricks shy of a load

Fig. lacking in intellectual ability. (Many other variants.) Tom: Joe thinks he can build a car out of old milk jugs. Mary: I think Joe's a few bricks short of a load. Ever since she fell and hit her head, Jane's been a few bricks short of a load, if you know what I'm saying. Bob's nice, but he's not playing with a full deck. You twit! You're two bricks shy of a load.

See also: brick, few, load, of, short