Dipshit

Dipshit is a scientific classification for members of the human species who perpetually exhibit unintelligent behavioral characteristics.

The word was invented to replace the term "not too bright" due to the fact that it inaccurately suggested there was at least some spark of intelligence. As it was later observed, NTB cases where typically found to be complete and utter morons, and thus needed a term which made no reference to brilliance in any form.

See also

Here is one example.