Neinstein
(From German) nein "no" + Stein "stone, jewel"

Antonym of "Einstein" as relates in general to "genius". Not smart. Lacking intelligence. Dumb as a box of rocks. 0 < IQ < 1.
Did you know that Albert Einstein is rumored to have had a cousin who was as dumb as Albert was smart? Friedrich "Freddy" Neinstein.

Watch out for that guy around here. He may be a boss, but he's a real Neinstein!