Fandom Tic

Those weird things and ideas that just keep cropping up in a fandom or Fan Community, over and over again. Like Fanon, but not. The little schticks that make it obvious what one enjoys, from Firefly Fen commenting on things being "shiny", through the Vulcan salute for Trek fandom, to those accepted mandatory scenes that every fanfic must include for it to be a true story of the fandom.

These are the sacred cows that can either be worshiped, or turned into burgers, depending on how one feels. They can also become Shibboleths used to separate the "true" fans from the posers, at least at first. When the posers catch on, though, the Fandom Tic might become incorporated into a stereotype for that kind of Fan.

Covers a multitude of sins, including memes, Catch Phrases, Memetic Hand Gestures, Sein Language, internally-originating Fan Community Nicknames, and Cosplay. When combined with Fan Fiction, it can overlap into The Stations of the Canon and result in Fandom-Specific Plots, for both of which it is a Super-Trope.

Please add examples under the medium of the original work or creator the fan follows, not the form of the tic.

Anime and Manga

 * Ranma ½ has had its share over the decades since fanfic writers have started going at it. Among others:  "I'm Ranma Saotome.  Sorry 'bout this."  Ryoga dropping in screaming "Ranma, prepare to die!"  Akane clobbering Ranma with a Hyperspace Mallet.  And every Alternate Universe Fic has to have its own variation on the "meet the fiancées" scene.
 * Ranma fandom was also very transgender-friendly decades before it was mainstream, due to the subject of the original work. From the start it attracted a larger percentage of transgender fans than other works; and in a few notable cases fan writers who made serious explorations of Ranma's sex-changing curse discovered that they had their own gender identity issues of which they had been previously unaware (or repressing).

Film

 * Perhaps the archetypal film example is The Rocky Horror Picture Show, with its ritualized-yet-evolving audience responses, cosplay traditions and devotees who attend midnight show after midnight show for decades.

Literature

 * For decades, "Yngvi is a louse!" was a meme/Shibboleth among pre-Net science fiction fandom.
 * Also from science fiction fandom, particularly along the East Coast of the United States: Buttons by Nancy Lebovitz.  Literally thousands of memes, all of which can be attached to your chest.  It is a rare fan indeed who showed up at a convention any time in the last four decades without at least one button by "the button lady" on his shirt -- to the point that the terms "fannish armor" and "fannish scale mail" were coined to describe those fans whose clothing was literally covered with buttons.

Live-Action Television

 * Star Trek fandom in its first decade or so was distinctively marked by the fans' use of the Vulcan salute and greeting ("Live long and prosper"). This seemed to fade away, except for nostalgic and perhaps ironic use, after the premiere of Star Trek: The Next Generation.  (Although it still remains part of the "Trekkie" stereotype, along with bad pointed ears and toy phasers.)
 * "Tea, Earl Grey, hot" and "Make it so" replaced "Live long and prosper" as Trek Catch Phrases for a few years.
 * "So say we all" enjoyed a brief vogue among fans of the Battlestar Galactica reboot, to the point that Edward James Olmos himself used the phrase when speaking before the United Nations in 2009.
 * Monty Python fans have a wide variety of Catch Phrases with which to identify themselves, from both the original series and the subsequent films.

Professional Sports

 * Name a team whose fans don't have some distinctive chant, cheer or other behavior.
 * For some bizarre reason, singing the theme song to the 1969 Pippi Longstocking TV show is a distinctive behavior of soccer football fans in Europe.

Web Original

 * Worm: Every fanfic must start with a "Locker scene". Every fanfic must include a power testing scene. [DESTINATION]...[AGREEMENT]....
 * In-Universe example: the Factions of Fenspace are Fandom Tics expanded into full cultures and civilizations.