While certainly not everyone who sees RHPS is queer by any means, the space these screenings are held in are basically assumed to be queer places, and the time spent there can definitely be described as queer time, I think. Characters in the film are of flexible sexualities and gender expressions, and because people seeing the film flock to it knowing this, the space created is queer-friendly by necessity. I've met people at RHPS who, when encountered in any other situation, are completely different people. The RHPS creates a space where people can laugh inappropriately at pretty much everything, where people can feel free to experiment with how they present themselves in a place where everything is met with acceptance and most likely encouragement.
RHPS is a very bad movie, but in a way that makes it more loveable, and the cult following that has grown up around the movie has created its own incredibly unique space for queering oneself. People who have never been to a Rocky Horror screening, or who is unfamiliar with the atmosphere surrounding the movie can't really understand why the movie has the following it does, but in the society we live in, the experience of Rocky Horror, of the ability to go to a movie theater and have an extremely funny and horribly inappropriate time, is a place where people can experiment and laugh and be themselves in ways they can't elsewhere.