How do you know if a guy is gay or bisexual?

I have a so called friend. He claims that he isn't gay and that he LOVES girls and pussy (which I dont disbelieve). But there have been time where he would say curtain comments to me. (ex. He would call me PHAT BOI, and also call me cowboy as well.) When I asked him about all of this stuff he's done, she would just say, "Im just playing with you." Also he would get mad if anyone else and/or I would called him those terms (PHAT BOI/Cowboy)