Acronym for Guy In Real Life.
Based on the belief that There Are No Girls on the Internet. Some forums, particularly male-dominated ones, will be the victim of a special breed of Troll who will pretend to be a girl just to rile up the boy nerds in the community. They display obvious Cam Whore traits and may even steal photos of attractive girls off MySpace or Facebook and claim that they are them.
In other cases they may copy photos of their sisters/daughters/nieces/female cousins off photo cd's or the like, especially if said females are of, or close to, the age of the online persona.
Female forum goers have a tendency to get a lot more attention, just by being girls, so many male attention whores use this to their advantage so that they get the attention they crave. They will play and flirt with the male members who may become tickled pink that a girl is talking to them this way. Sad, but true.
Will ultimately lead to a reveal where they show their true colors as blokes and laugh at the incensed regulars. Or, a Regular will wise up to his shenanigans and unmask him causing everyone to point and laugh at him as he slinks away with his tail between his legs. Could also be a practical joke played by a Regular to which everyone will simply have a good laugh. Most cases tend to end in the second case, which brings up the question of why such trolls even bother doing it since the risk of being exposed far outweighs the potential gain.
Naturally, any mention of online dating in the "Old Media" will end this way, whether played for laughs or for drama, because everyone knows the internet is solely the domain of perverts.
If you think this is bad, though, be grateful you're not dealing with a Mailer Daemon.
Note that not everyone who's biologically male who presents as female online is trolling; see Cross Player, Transsexual. Leads to actual women on the Internet using male or neuter user names and fudging personal details specifically to avoid this trope.
This is often inverted on many female dominated forums, such as LiveJournal, where the default identity of new posters is assumed is female, and a guy, who acts normally but doesn't explicitly mention he is a guy, can go for a long time without anyone asking or realising, leading to "You're a guy??" moments 6 months down the track.
See also Faux Yay.
.hack//SIGN completely inverts this as being the major "twist" of the series. As well as it being a case of amnesia (sort of).
Well, it's not really played as a twist—it's brought up early on, then rejected but only by the character in question saying "Of course I'm not a girl!" So when it's revealed that the initial theory was right all along it's not very surprising.
A better example is Saburou from .hack//Roots. She actively claims to be female and states that she simply acts like a boy because many boys act like girls in the game when called out on it due to her male name and male way of speech. The fact that she's on this page means of course, she is male in the real world. It's even pointed out on her character design for Link where her head band is adorned with the male symbol.
Durarara: Like any good troll, Izaya poses as a girl on the internet.
Discussed in vol 9 of the Light Novels between Bakyura and a new member, who's probably doing this, too: "she" is hinted to be Aoba. The kid's really taking after Izaya...
At the beginning of Nyotai-ka, protagonist Manaka Makoto is a nekama, a young man who, frustrated by his inability to attract the interest of women, masquerades as one on online dating sites for amusement. Hilarity Ensues when a goddess intervenes and suddenly, it's no longer just an act.
In Ghost in the Shell 1.5 Batou is net-dating a sexy young woman who's actually a ninety-year old man.
A quick scene in episode 1 of Sword Art Online has a Mirror item reformatting all of the player's VR avatars to reflect their actual selves from Real Life. One quick scene shows a crowd of girls suddenly revealed to be mostly men using female avatars, and there is a minor Running Gag of a specific couple composed of a cute girl revealed to be a skinny man and a lean boy revealed to be a pudgy man who remain friends despite the shocking reveal, and later reunite after the end of the Incident in real Life as friends.
Comic Books
In Ultimate X-Men Beast gets into a relationship with a girl on a chatroom...who is actually the Blob, one of Magneto's henchmen, pretending to be a girl for kicks (a mutant genius supermodel, no less). Then Henry accidentally blabs about how Xavier brainwashed Magneto. Oops.
Out Cold has two men who pretend to be lesbians meeting each other in a chatroom. Naturally, they have cybersex.
In Surrogates, the operator of the seductive female surrogate at the nightclub that got fried happens to be a man. The characters don't treat this "revelation" as unusual or noteworthy in any way.
In Gamer, Kable's wife, a character in Society, is being controlled by Gorge, a topless and terribly obese home dweller.
Literature
Trilby and the Ghost, a short story by Yahtzee taking place in the Chzo Mythos'verse, involves Trilby discovering a ghost who can't pass on to other realms because he's never met his japanese girlfriend Nariko face-to-face. Predictably enough, 'Nariko' is actually a southern gentleman named Frank, which only makes Trilby's job more complicated.
A variant: In Animorphs, a mission requires hacking the identities of people on an apparent anti-Yeerk website. While doing so, Marco takes an extra moment to look up his online girlfriend, who is naturally a seventy-three-year-old retired postal worker. (He doesn't mention gender, so presumably still a girl, though.)
Live-Action TV
Psych: Shawn and Gus pretend to be a woman in an online poker chatroom and arrange to meet one of the other players. The guy from the chatroom laments, "Man, all hot women on the Internet are guys! Only you're two guys, which is weird."
In an episode of NCIS, McGee develops an online relationship with a girl who turns out to be DiNozzo playing a prank.
At the end of the episode, Ziva tells McGee the truth, but since Tony had grown sick of the prank, McGee takes revenge by playing along just to mess with DiNozzo.
In a prior episode, DiNozzo admits to having cybersex with a person called HotJugs24. The name probably should have been his first clue.
Subverted in the 1990s Jerry Springer parody Night Stand, where two straight guys met online pretending to be lesbians revealed themselves to each other... and decided to date anyway.
In an early Buffy the Vampire Slayer episode, Xander expresses suspicions about Willow's new cyber-pal.
Xander: I mean, sure he says he's a high school student, but I can say I'm a high school student.
Buffy: You are.
Xander: Okay, but I can also say that I'm an elderly Dutch woman. Get me? I mean, who's to say I'm not if I'm in the elderly Dutch chat room?
Their suspicions turned out to be correct. "Malcolm Black" was actually the demon Moloch the Corruptor.
On the Israeli sitcom Shemesh, the titular character, having recently discovered the internet, pretends to be a woman on a women only chatroom, mostly for the thrill; he stays there for the more honest intention of learning how to relate to women. Hilarity Ensues.
An episode of Scrubs had an intern talking to a girl online only to find out it was a man. In response, he created a new account, pretended to be a girl, and got him to arrive at the hospital.
In The Big Bang Theory, Wolowitz meets a slutty troll in an MMORPG. It's the creepy janitor at the University.
An episode of Malcolm in the Middle has Craig give Francis a tip for free travel. Pretend to be a girl in a chatroom, flirt with a random guy from the location they want to go and then ask him to pay for a plane ticket so they can meet up. The last scene of the episode shows Francis getting off a plane and saying "Thanks" to a guy holding a flower and a card saying 'Debbie'.
In the British sitcom My Family it's mentioned that this has happened to Nick, and most of the others think the same of his current online girlfriend. A Subverted Trope as she turns out to be a genuine... lesbian. Nick himself was the GIRL.
In The Teaser of an episode of The John Larroquette Show John goes to an internet lesbian chatroom pretending to be a woman.
John (typing): What are you talking about?
Girl 1: [something mundane]
John: Sounds hot.
Assorted girls: MAN IN THE FORUM! LOG OFF!! LOG OFF!!
Flash Point: A robber with an anti-capitalism bent is desperately lonely when he meets a sympathetic girl online — she even sings a song for him. It turns out "she" is a teenage boy who really, really, really hates his stepfather and is using the robber to murder him by saying "she" is being abused (no one's being abused, he just hates his step dad that much).
An epic example in Gossip Girl. The titular blogger turns out to be Dan Humphrey.
Jokes
On the Internet; men are men, women are men, and children are cops
Music
This is the idea behind Frogg Marlowe's song "Ain't No Women":
After setting up a date with a girl he met online, the protagonist of the song "On My Knees" by Heavens Gate finds out she's actually a man.
Hello champ, my name is Jack!
In the song "Chiksilog" by the Filipino band Kamikazee, one male Ragnarok Online player was distraught when he discovered that the "girl" he met online turned out to be Camp Gay.
Overheard in a city chat on World of Warcraft: "Welcome to the internet, where the men are men, the women are men, and the children are FBI agents."
A study from the Daedalus Project shows 45% of female World of Warcraft characters are actually played by females.
Interestingly enough, even though women make up about one-third of the playerbase, the number of male and female characters in-game is almost exactly fifty-fifty. The reason for this is that approximately one-third of male players use female avatars, whereas only ten percent of female players use male avatars.
In the comedy column "Ask A Faction Leader," someone asks Chronormu (whose model in-game is a female gnome) about her masculine name. Chromie responds by explaining that she is actually a he in his dragon form, and only uses a female form to interact with mortals because "if you had to spend multiple hours each day running around performing thankless corrective tasks on Azeroth, wouldn't you want to do it as something fun?"
Any player of any online RPG may cite that their acronym aptly describes their population: Mostly Men Online Role Playing Girls.
These days this has been somewhat muddled, as close to 50% of the MMORPG players are starting to be women (apparently they are among the most popular "real" video games among the female populace), but often play as men due to either sexist character designs or horny teenagers hitting on them.
Played straight and subverted in one of its oldest forms. On the Original TinyMUD, back in 1989 there were only male characters. Then within about 3 weeks, a bunch of women showed up. about half of them was a single, actual teenage girl, Claire. Almost all the rest were played by guys.
Webcomics
In thisPenny Arcade comic strip, Gabe explains to Tycho how he is being "paid to infiltrate forums and regurgitate press releases as a trusted source". He informs him that he is posing as Shelly Yu/Missfit<3, a "tween" who enjoys games, making friends and "just having fun" and trusted member of the IGN Boards.
There was also one strip in which Gabe where he warns against "roleplaying" with others to Tycho's niece, mentioning that he'd done some odd things with night-elf ears during such.
Much earlier in the story, Francis also pretends to be a girl called Sasha online.
Before the first Tomb Raider game came out, the main developer gave that as the reason why the main character was made female. Of course, he's British, so he said 'bum' instead of 'ass,' but that's what happened.
Interestingly enough, Brian Clevenger from 8-Bit Theater also once said the same thing in regards to the same game almost word for word.
In Megatokyo, this is used - in a rather twisted fashion - during a flashback. Piro plays an MMO with a male character, starts chatting with him outside the game, and eventually starts to wonder if 'he' isn't actually a girl... eventually, he seizes on an opportunity to ask him for a picture. He gets it, and sure enough, 'he' is a cute girl, whom he starts to fall in love with. Then she dumps him by revealing that she's actually a guy, the picture was fake, and she was just playing with him for kicks. The twist? The picture was real, and she really IS a girl. Exactly why she pretended to be a G.I.R.L. is, as yet, unknown, but Piro is still pissed at her for pulling that stunt...
Also, Piro himself is cross playing, and out of the flashbacks, Miho tells him that she sometimes believed he was really a girl.
Both inverted and played straight in Something Positive. Branwen manages to convince an entire forum that she's a man, causing all the female forum-goers to fall in love with her. Upon learning of this, Davan decides to further troll the forum by pretending to be female and posing as Branwen's male persona's lover.
Although this seems like a majorJerk Ass move, it also helped those women to move on, rather than pine for a relationship that could never be. Some of them had been waiting for years for Branwen's male persona to return.
Got a nod in the joint That Guy with the Glasses/Mystery Science Theater 4000 riffing of the Chinese Dragon Ball movie. "Oolong" shapeshifts into "Bulma" to get the "Dragon Pearl" from "Roshi"; the riff is "You know, this is an accurate depiction of most Internet relationships: one's really a guy, one's really a really old guy."
Yu Gi Oh The Abridged Series - Tricking people into cybersex by pretending to be a girl is one of Yami Bakura / Florence's hobbies. Then he ends up doing it with Marik completely by accident.
Ian plays a female character in the Statless And Tactless group's RP sessions. It's presented as harmless.
In Brazilian website chargesdotcomdotbr, there was a story featuring a character nicknamed "Espinha", who entered a chatroom for lesbians and scored a date. When he went to talk to a friend for an advice on how to tell his date the truth, he learned his friend (also a male), was his date.
The (male) creators of a neural-net evolutionary-algorithm checkers-playing program wanted to test their software against real players, so they created an account on Micro Soft's online gaming portal The Zone. To make sure they'd get plenty of responses, they used the account name Blondie24.
