plastic empty head

Term for someone who is open-minded enough to adopt an untenable theory (often some kind of crackpot conspiracy), yet close-minded enough to reject all criticism of that theory. The combination of echoing empty space and solid, impenetrable plastic makes rational communication impossible.

I tell you, this Illinois lottery result proves that Obama is the antichrist. You're wasting your time arguing with me, I have a plastic empty head.

Plastic head

A politician with so much makeup and wax that he looks like plastic

That fucking Lindsey Graham is a true plastic head