I dunno... I have always been straight, and my junk always twiched when I was around females. But gay people I know, have said that their junk just always twitched when they were around other males.
I don't know how any straight male (beach bum allegedly) could claim to "know" what makes another man's junk twitch. And, even if somehow you had access to another man's tingle register... why would ya care?
Doesn't matter to me. When two guy bump uglies, it just means there are two girls out there who can't fine the pipe when they need it. So it's a good thing. I'd be cool with about 3 billion men going for the meat tomorrow... I wouldn't mind 3 billion ladies lining up for it.