What is "straight-acting"

a. Of a gay or bisexual man (or, rarely, of a lesbian), having the appearance, mannerisms, etc., of a stereotypical heterosexual of the same sex rather than those stereotypically associated with gay men or lesbians.

Straight-acting is a term for a LGBT person who does not exhibit the appearance or mannerisms of what's seen as typical for gay people. Although the label is used by and reserved almost exclusively for gay and bisexual men, it may also be used to describe a lesbian or bisexual woman exhibiting a feminine appearance and mannerisms. Because the term invokes negative stereotypes of gay people, its application is often controversial and may cause offense.