A person, most likely living in the basement of his/her parents, that claims to like neither men or women in the real world but does, however, enjoy masturbating to porn.
A: "My mate nearly made it with this really hot girl yesterday, but he blew her off for jerking it to porn at home."
B: "Whoa. He must be gay!"
A: "No, he isn't into real-life relations with neither men nor women, he's pornsexual."