So this is what happened?

Also the answer to the question in the OP is no. Your brother is probably messing with you for the laughs.

My assumption is that he's making a goof about the reason she likes the idea of man on man.  If she liked man on man because that means more women left out there for her than yeah that'd be lesbianic.  However if that were the reason you liked the general concept of man on man you wouldn't watch it, there'd be no reason to, you'd just like the idea that it's out there somewhere helping you score more ladies yourself.  

I haven't seen a penis outside the locker room in many-a-year. My secret? The Maddox thumb trick.

http://books.google.com.hk/books?id=cMaoUumZOd0C&pg=PA182&lpg=PA182&dq=maddox+thumb+trick&source=bl&ots=okVGJLqS-H&sig=NnjxtJCckErlPscJnsjLDIcFdzY&hl=en&sa=X&ei=kAhzUPbaOoWhiAfgnIHwBA&ved=0CCcQ6AEwAQ#v=onepage&q=maddox%20thumb%20trick&f=false

(Images have been edited out... whether this is for copyright or offense reasons, I do not know).

Now that you know, any erect penis (which isn't yours) that you see is entirely optional. That is, if you see another man's penis on your screen, that was totally your choice, and you may need to talk to somebody about this.

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@OP: Yes, it makes you a lesbian, but only after there are many, many dudes on the screen. Why? The law of diminishing utility.

The first penis has positive utility, let's say it's 100.
The second penis has a positive utility of 60. You enjoy it, but most of your excitement would have been there with just the one.
Third penis is utility of 40.
etc,. By the time you get to seven or eight, any additional penises add no additional benefit.

Then we get into the realms of negative utility. Imagine beers, the first few have high utility, but utility starts falling fast. After a while, beers have very little positive effect, but greatly increase your chance of vomit. That is, the negative utility becomes higher than the positive utility. So, utility diminishes to negative.

I imagine the same rings true for penises. So, once you get to 10 or so penises, they start to have a negative utility. By about 15 or so, the total utility derived is probably in the negatives. A negative penis is a vagina. If you watching porn with fewer than 15 penises, you're probably straight... one more penis and you're going to hell, missy.

(This post had the word "penis" included 12 times, and "vagina" once. I think this roughly balances out as being a just-about-straight post).

You like to over analyse everything don't you?

I couldn't help myself but try to think of what logic the brother could possibly be using, this is the best I came up with.  

My assumption is that he's making a goof about the reason she likes the idea of man on man.  If she liked man on man because that means more women left out there for her than yeah that'd be lesbianic.  However if that were the reason you liked the general concept of man on man you wouldn't watch it, there'd be no reason to, you'd just like the idea that it's out there somewhere helping you score more ladies yourself.  

Alternatively, NFG made up her brother's (Bacon's?) statement to tell us that she enjoys gay porn more *ahem* subtly than last time

ಠ_ಠ