An effeminate straight male. A genuinely straight flamer isn't a gay man in denial, but rather, genderqueer and/or androgynous. He enjoys the company of gay men and women, and has probably had plenty of opportunities to be with men, but singularly desires women. He enjoys the duality and expansiveness of feeling both masculine and feminine, and likely feels like a lesbian in a man's body. Finding a woman who desires this kind of man, however, is the straight flamer's burden in life, but they do exist.
"My gaydar totally misread that guy. I would have sworn he was gay, but he's just a straight flamer." Sorry, hon.