1. Conventionally masculine. Describes a homosexual male whose behaviour resembles that of the traditional heterosexual or straight male stereotype. Often considered politically incorrect (or even homophobic) as a label, but can be used facetiously. May apply to gay males who exhibit conventional masculinity out of a genuine predisposition, as well as to those who affect it out of insecurity (sometimes to remain in the closet).
2. The gay male equivalent of the lipstick lesbian. As a social phenomenon, the "straight acting" homosexual breaks from gay stereotypes in a way comparable to the metrosexual's defiance of straight stereotypes. (Both labels rely on stereotypes in order to be understandable, even as they describe non-stereotypical behaviour.)

A gay or lesbian who has to pretend to be straight in order to avoid persecution.