Cement-headed straight clown (dictionary)
From BoyWiki
Cement-headed straight clown, or more often CHSC, is a colloquial term used to describe a heterosexual person who, never having had to question his own sexuality, has lost all capacity to reason and think open-mindedly. The brain of a CHSC, it is humorously implied, has turned to cement and has become unable to yield. First coined on BoyChat by Adam Selene, the term is used for individuals who, upon hearing of boylovers, immediately start to make all kinds of assumptions, often lashing out with condemnation and foul language.