A nickname for the Commodore Business Machines logo, which resembles a poultry part (rendered in ASCII as "C="). With the arguable exception of the Amiga, Commodore's computers are "notoriously crocky little bitty boxes" thus, this usage may owe something to Philip K. Dick's novel Do Androids Dream of Electric Sheep? (which was the basis for the movie Blade Runner, and the book is now sold under that title); in that story a chicken head is a mutant with below-average intelligence. STMRTB.
NetLingo Classification: Online Jargon