| Chickenhead is a term used in the book "Do Androids Dream Of Electric Sheep?" by Philip K. Dick to describe a person who is on a very low end of the IQ test that is administered to all citizens of Earth. Chickenheads, due to their low IQ, are not permitted to emigrate to an off world colony, and are doomed to expend the rest of their lives on the barren and poisoned Earth, generally in a dead-end, low-paying, self-diminishing job.
J.R. Isidore is a chickenhead. John works as a truck driver for an electric animal hospital, and his crowning achievement in the book was to be the one who gives a phone call to a person whose real animal had just died. John did not want to make the call, but his employer, an anthead, forced him, under the threat of being fired if he did not. After making the call (which was a tremendous and frightening labor for him) he gains a bit of dignity and self-respect. This self respect would later paramount when he comes to the aid of three escaped Nexus-6 androids.
It seems that when Dick was writing the story, he was comparing the chickenheads of the year 2021 with the working class of our own time. Both are generally easily influenced, and have little notion of their own value and self-worth. Perhaps he added this to the book to criticize the way people higher up on the scale treat the chickenheads.
Oh, yes, J.R. Isidore does not like being called a chickenhead. | 
