This trope holds that the primary demographic for video games is males ages 15 to 25, which explains why games are full of male-only Fanservice, especially in the form of Stripperiffic female characters, gratuitous violence, and concepts that are oriented more to explosions and racking up a high body count than plot or character development.
"The belief that boys shouldn’t be interested in girl things is the main reason there’s hardly anything decent for girls in animation — or almost any media for that matter. It’s a backwards, sexist, outdated attitude."
—Lauren Faust, creator and former executive producer of My Little Pony: Friendship Is Magic
Mainly, the Double Standard most people have regarding media: that women's entertainment should only be enjoyed by women with no crossover allowed — despite it being okay for women to watch shows primarily marketed towards men — keeping in mind most media is male-focused. Not to mention the stigma that media specifically tailored for women is 100% guaranteed to be of inferior quality, no exceptions.
This line of thinking is very clear in most creators and executives' minds. Men and women could watch shows meant for men/starring a man, only women could like a female-centered, never mind "girly", show. Watching a girl show would be unmanly and be subject to ridicule. Just watch any show and the guy who's the more sensitive and caring member of the cast is usually the Butt Monkey.
And by virgin, we almost always mean a female virgin. Because male virgins don't exist. Ever.
Note that the term "virgin" originally meant "a female who has not had sex with a man", and thus literally no male was ever a virgin — which sort of underscores the trope. The definition became more vague as language evolved.
Sex as Rite-of-Passage: The character is desperately trying to have sex to establish his manhood.
All Men Are Perverts: A man could never not want to have sex with a woman.
Louis Ciccone: Your honour, may I approach the bench?
Judge: You've been watching too much American TV, Mr. Ciccone. No one "approaches the bench" in a Canadian court.
—Seeing Things note
A special case of Reality Is Unrealistic, Eagleland Osmosis occurs when people outside the United States consume American pop culture and start to believe that aspects of their own society work like they do in these imported films and television shows.
The most common forms of this concerns the legal system, with people expecting to be "read their rights" if they are arrested, expecting that police should have a search warrant in cases where they do not need one under local law, or calling a serious crime a "felony". Another one is expecting 9-1-1 to be the number for emergency services, even when the actual number is usually displayed prominently on phonebooks and phone booths.
This isn't new, or limited to the United States—it's a side effect of World Power status. Elements of the major power's culture and language bleed into the popular culture of other countries. The Japanese adoption of Western customs like Christmas, Valentines Day, and wedding ceremonies is a good example. In older tales, an astute reader will find Limey Osmosis, Frenchie Osmosis, and even Kraut Osmosis. Granted, modern mass media and the Internet certainly accelerate the effect.
In fiction, characters inevitably come out with well-formed sentences. They may have a poetic flavor filled with William Shakespeare-like similes and luminous golden metaphors that most people in real life aren't clever enough to come up with on the spot or even at all. They never stumble over their words or say the wrong thing except for deliberate comedic effect. Even "realistic" dialogue is relatively free of errors and padding. It's almost as if it was written by a professional. (It really was.)