Boy I can see many sides to this.
I bet we all could name several things we haven't experimented with, and would never experiment with. I mean, there are a lot of things out there. We can't possibly try them all.
Have you experimented with ceramics? bass fishing? wood turning? sky diving? grappa, restoring antique hammered dulcimers, rugby, coprophagia, contract bridge, harness racing, rocketry, motocross, fisting, escargot, peppadews, tapas, snowboarding, curling, bestiality, titty fucking a pre-op transexual? . . .If I experimented with frottage with a dolphin would I be hooked?. Do I really need to try out a prince albert before I can honestly declare it's not for me? do they even allow returns?
So. . .what is it that drives us to experiment with some things and ignore others? There's got to be some difference. Let's call that difference "interest".
Even though you haven't tried something before, you have to have at least some interest in order to motivate you to go ahead to the next step and experiment, which will either strengthen your interest, weaken it, or kill it altogether. But the point is, some interest has to exist before the experiment.
There really are guys (I'm not one of them) that really do have zero interest—I'm talking 0.000 interest level—in erotic activities with other guys. Not even enough to bother with experimenting. Many of these truly, genuinely, 100.00% heterosexual males see their heterosexual status like a perfect game in baseball. If someone gets even one base hit off of you, even early in the 1st inning, you can't be credited with a perfect game.
On the other, um , hand, it's not like we have an official sanctioning body keeping score. We all have different opinions and criteria. For example, teen web forums are full of threads like: "Is it gay for a guy to...", "Is it gay for a guy to think about...", I've even heard old guys say that when they were a kid they debated if it was gay for a guy to jack off (the reasoning being: It's gay to give a guy a handjob, even though you're alone, you are still a guy, therefore it's gay). These scoring disputes can get complicated.
Hopefully all this ambiguity will force people to have meaningful conversations about their sexuality; rather than simply checking a box for "straight, gay, or bi", maybe we'll start showing each other our full pie charts. For example, I like how this forum lets you give percentages. I find it encouraging that so many guys here are able to admit their small percentage of "gay"-ness. I suspect many of those guys would have checked the "straight" box if the only choices were straight/gay/bi.
Even though I do have a small amount of interest in guys, I usually identify myself as straight in casual conversation, where there's no opportunity to elaborate. It's not just easier, it's the most truthful short answer. It's like someone asking "how you doing"? Even if I have a mild headache at that moment, I still say "fine". I don't feel like I'm living a lie if I do that.
To get back on topic... From the comments here, It doesn't seem like guys with Big Ones are more prone to experimentation, but if they do, their Big One is almost always the icebreaker/conversaton starter that gets things into a sexual mood. It's such a reliable play, why not run it as often as you can? I don't have a Big One, so this is just an educated guess.
When guys are mostly straight, it's often hard to get things rolling without seeming too gay. It's suspicious for a straight guy to be interested in cocks, however, there is a loophole in the "Guy Rules" to allow a certain amount of banter about unusual penises, big, small, differently shaped, etc.
For example if a Big One should somehow come into view, either live or on video, even the straightest guy is allowed to joke about it, then make even more serious comments about it. Letting the other guy(s) "accidentally" see your Big One seems like a great way to trigger this whole process, while retaining plausible deniability if you have to scrub the mission.
A video application of the loophole: me and buddy clothed, watching straight porn, which we've done before but never any j/o. Tom Byron getting a long BJ , and my buddy says "where did his balls go?". I explain it to him, he says "but a guy can't stay like that for that long, it must be in the editing"...
Perfect opportunity for a mutual jerkoff in the guise of an edging technique lesson, AND since its a "lesson", there's a plausible reason to stare at each other the whole time. Kind of like "spotting" for your workout buddy in the gym. If I had just suggested we jerk off together, or just pulled out my cock, he would have freaked and I'd be the bad guy.