BRAIN-DAMAGED [generalization of "Honeywell Brain Damage"
(HBD), a theoretical disease invented to explain certain utter
cretinisms in Multics] adj. Obviously wrong; cretinous; demented.
There is an implication that the person responsible must have suffered
brain damage, because he should have known better. Calling something
brain-damaged is really bad; it also implies it is unusable.