"Guys can't cum as often compared to girls, so of course they aren't horny like us! We're the ones who get pregnant and give birth, so if we aren't born horny the world will end!"
I love how this rationalization makes total sense in their world. In fact, it "makes sense" even in our world, and yet it's completely wrong! Remember that next time you trust your "common sense" or intuition on factual matters.
"I bet all this time you've been masturbating to things like nude gravure in gossip magazines."
Maybe I'm just not well-read enough, but this manga sometimes has the smartest comedy I've ever seen. The girls don't act completely like the men in our world do because this isn't a completely genderswapped world. They still read gossip mags as our stereotypical women would, the only difference is in the nature of the sexual content (being more visual like what appeals to our males). Seriously, this is one of my favorite chapters of any manga ever.