That's what my friend told me as we were waiting for The Dark Knight (which was pure awesome!) to start screening last weekend in a cinema in Greenbelt 3. And I have to agree since I saw several groups of PLU guys at the theater that night apart from our group. I even saw one of the gay bloggers with his boyfriend there with their friends. Hehehe. (For those living under a rock, a Grand EB [eyeball] is a party held so that people patronizing an online venue, such as IRC channels or sites like Guys4Men, can meet each other in the flesh for the first time.)
Of course, I'm not 100% sure that all of the guys in those groups are non straight, but even my limited powers of gaydar have picked up tell-tale signs. A good sign was the attire: quite a lot of the guys wore really sexy, tight-fitting, and attention-grabbing shirts. Another is the group dynamics: guys tend to lower their inhibitions and become less discreet when they're with their friends. There's also the fact that a large group of guy friends, without girl dates, has a higher probability of being a PLU group in upscale places like Greenbelt.
What's the moral? If you're the ultra-discreet guy, then avoid these obvious signals! Then again, try to loosen up and not be so uptight! Being too self-conscious is no fun at all.