WHY? I've been to jack off clubs many times, and they're always awesome. I've also had plenty of experiences jacking off with guys at the gym, in the sauna/steamroom. These things actually do happen in places and they're great. If all guys would ease up and jerk off with their buds, the world would be a better place.
That said, I agree that jerking off with guys doesn't necessarily mean you're gay. Of course, I think labels like "gay" aren't particularly helpful; it's all a continuum, and I consider such "pigeon-holing" harmful.