All men have some curiosity about penisis (peni?) it occurs naturally. As we evolved, and left crushing someones head with a rock behind,(to see if we measured up). Small boys, and I'm sure bigger boys who have been drinking beer, often try to out pee their peers. It's pretty much the same thing. Curiosity about how we measure up is not a big jump from that activity and fundamentally human.
I suspect, that the normal locker room "furtive glance" is a form of risk assessment innate to the human male brain. It is not something we can avoid. Ok, if you concentrate on not noticing; but drop your guard and the auto process assessment will continue.
Hence for truly straight guys, LPSG is just a cyber locker room. For the rest of the population, likely 80% of men; it has a deeper meaning. That's not saying that a significant portion of that 80% will actually act on it. But for that 80% there is an attaction present not felt by the truly straight minority.
There is no right or wrong in sexuality (paedophillia excepted). The fact that confident straight men are on this board and engage in spirited discourse (carefully treading around the word "intercourse") with others who identify as bi or gay; has given me hope that our society is evolving towards a better place.
Great discussion guys!