Social Homophobia

The fear of being identified as gay can be considered as a form of social homophobia. Theorists including Calvin Thomas and Judith Butler have suggested that homophobia can be rooted in an individual's fear of being identified as gay. Homophobia in men is correlated with insecurity about masculinity. For this reason, allegedly homophobia is rampant in sports, and in the subculture of its supporters, that are considered stereotypically "male", such as association football and rugby.
These theorists have argued that a person who expresses homophobic thoughts and feelings does so not only to communicate their beliefs about the class of gay people, but also to distance themselves from this class and its social status. Thus, by distancing themselves from gay people, they are reaffirming their role as a heterosexual in a heteronormative culture, thereby attempting to prevent themselves from being labeled and treated as a gay person. This interpretation alludes to the idea that a person may posit violent opposition to "the Other" as a means of establishing their own identity as part of the majority and thus gaining social validation.

Nancy J. Chodorow states that homophobia can be viewed as a method of protection of male masculinity.
Various psychoanalytic theories explain homophobia as a threat to an individual's own same-sex impulses, whether those impulses are imminent or merely hypothetical. This threat causes repression, denial or reaction formation.

http://en.wikipedia.org/wiki/Internalized_homophobia#Social_homophobia