why do straight guys find girl-on-girl action hot, almost universally?

If two women is twice as good, why not three? Or is a crowd un-sexy?

I don’t really find it attractive. Yes, there’s two girls, but that just means there’s no (potential) room for me. When I see guy-on-girl, I can at least mentally put myself into the act, substituting the dude for me. Two lesbians don’t want a guy.

On the other hand, I briefly knew two bi girls who liked each other and liked me. When they pawed each other, that got me going, since I knew I wasn’t automatically excluded from the fun.

Yep, all of the guys have said it way better than I. For me, I don’t have the sausage getting in the way of me fantasizing being in the action somewhere.

No good. Too many people.

I like to look at beautiful women.

I like to look at beautiful naked women.

I like to look at beautiful naked women having sex.

I’m not all that crazy about watching some guy having sex.

Hence, two girls having sex is, as I said above, twice the good stuff and none of the bad stuff.

So you drink them both at the same time?

Hell yeah! Next question.

It’s not just that there’s two. Then 4 women should be twice as hot as 2, and for me it’s not.

I don’t worry much about why I find two women so hot, but the OP’s analysis that the overt, unashamed embracing of something slightly taboo makes sense to me. It’s also true for me that two women who are not model-looking types, but are really and obviously turned on when they get together is incredible, while model-types who are going through the motions are not. That seems to fit in with the OP’s guess, too - two women who are sharing something and letting themselves be vulnerable, even as another watches.

Of course. Cite: http://foodcourtlunch.com/wp-content/uploads/2007/09/beer-hat.jpg

Lesbian threeways are also a common porn motif. Seriously, this is like a college class where nobody’s done the required reading.

I have noticed that a porn threesome has a unique problem – one of the three is usually blocking the camera.

MrPanda has never been impressed with hot lesbian action. He’s very much for girly bits but prefers just one set o’ everything.

shrug

Maybe it is because I used to date a girl who turned out to be bisexual, but it does nothing for me.

I believe this was best addressed on that old show, Mad About You:

“It’s fun, it’s sexy, and I agree with both of them.”

Yep. It’s Rule Two in the Three Rules Of Male Thought.

Rule Two states that if one is good, two must be better. It also explains the tinkering and screwing around that males, especially young ones do. For example, you have a chemical reaction that produces an explosion. Do you, male human, put the stuff aside and go on the next thing, or do you double the ingredients and try to rearrange the roof?

…And you wondered why you only had 7 fingers left…

Partly as said I think it’s because there are no males involved. And partly, I think there’s a little subfunction in the brain that runs on an equation of gender I find attractive + sex = good. So, for a straight man women making out with each other is a turn on because they are members of the sex he finds attractive acting sexual. And there’s quite a following among straight women for guy/guy action as well. But the effect isn’t noticeable among gays and lesbians because guy/guy or girl/girl action is what they like all the time.

It’s simple math.

Straight guys like watching women in sexual situations.

Watching one woman in a sexual situation is nice but it’s watching masturbation not a full sexual situation.

Watching a woman and a man having sex involves watching a man in a sexual situation. As I pointed out above, straight men want to watch women not men. So the man here is not contributing anything to the entertainment.

Watching two women having sex is the peak. We get the positive of watching women in a sexual situation without the negative of watching a man in a sexual situation.

Watching more than two people can become distracting.

This is a quality control issue. You need to upscale your porn.

This is a perspective issue. If the camera is far enough back to capture 4 women going at it, the relevant details are too small to be really appreciated. Closeups are critical.

I had a friend whose favorite genre of porn was “gang bang” videos - videos where a group of men would all have sex with one woman. As I used to point out to him, this was just one woman away from being a gay orgy.

I feel that anything more than a threesome is too much – either the larger group splits up into smaller ones, or it’s a writhing mass of flesh that’s kinds hard to even identify.