"Steve learned the hard way that all his jokes for TV had to be about events that had been made much of by TV itself, and very recently. If a joke was about something that hadn't been on TV for a month or more, the watchers wouldn't have a clue, even though the laugh track was laughing, as to what they themselves were supposed to laugh about." —Kurt Vonnegut, Timequake
On the subject of contemporary music, film, television, and (to a lesser extent) sports, television characters can comfortably mention all kinds of people, expecting that most, or at least enough, of the audience will know whom they're talking about. On most other matters, however, their world becomes very small; TV producers fear any comment that might ever go over anyone's head, and thus only the most obvious and world-renowned people and things are allowed a mention.
It's worth noting that a major work of pop culture can completely turn one subject around and make it a free-for-all. For instance, before Jurassic Park, many people had only heard of maybe three or four types of dinosaur. Afterwards everyone could suddenly discuss velociraptors and dilophosaurs as though they'd known about them since childhood; a new NBA franchise even named their team "Raptors", signaling that the species was there to stay on the pop-culture radar. The works of Leonardo da Vinci got a similar treatment thanks to Dan Brown's The Da Vinci Code.What is obscure varies depending on time and place. Shows from the 70s and 80s will assume that people will know about figures like Augusto Pinochet and Leonid Brezhnev, but one can't assume the same anymore, while references to certain American personalities in Family Guy or Robot Chicken will fly over the heads of viewers from elsewhere.
One notable case where all these qualms about obscurity get thrown out the window is the Celebrity Star. It's much easier to get a guest who's "famous" than one who's actually well known. If a band makes an appearance, most of the characters will suddenly become fans, no matter how obscure or washed up the band really is — which can also lead to such hilarious situations as the City Mouse suddenly liking country music or the wholesome, mostly white, Dom Com family all loving a rapper who is not normally known for being family friendly. Likewise, B- and C-list actors are all suddenly big stars when they walk onto a TV show and everyone will know them by their real names.
Musical examples of these are often used as Standard Snippets.
A Super Trope to Nothing But Hits, Small Taxonomy Pools, Geek Reference Pool.
A Sister Trope to Weird Al Effect, Public Medium Ignorance, Cultural Cross-Reference, Popcultural Osmosis, Eiffel Tower Effect, Everybody Knows That. Depending on how small the reference pool is, this can sometimes lead to certain works being a Shallow Parody of the genre or medium they're referencing.
Contrast Genius Bonus.
During time travel encounters, all events of historical importance after 1900 happened in America (or possibly Germany, but only if Nazis are involved). Before 1900 all events of historical importance, or at least those not in America, happened in England, Rome, or occasionally Greece. Every event of historical importance that took place in the U.S. between 1800 and 1900 took place in one city.
When it comes to science-fiction writers, you can count on just about everyone having heard of one man: Ray Bradbury, author of The Martian Chronicles, a collection of short stories that has been adapted into several other media. Arthur C. Clarke tends to be less well known, even though he helped to write the screenplay for 2001ASpaceOdyssey – a film that most people know through at least Pop-Cultural Osmosis. Hardcore Star Wars fans usually are familiar with Timothy Zahn, Kevin J. Anderson, Steve Perry, and perhaps Alan Dean Foster.
This mostly shows up on a cultural level: people will be aware of the dance styles of the culture they grew up in, and that's it.
For Americans, dance is the waltz, the tango (only because it was once banned for obscenity), ballet (which began and ended with Tchaikovsky), and maybe hip-hop/street dance. In areas with a large Latin American population, there may be awareness of dances like salsa, samba, and rhumba as well.
And there will never be a mention that most of those are styles and/or families of dance, not individual dances themselves.
For those special occasions, it's always a bottle of champagne (which technically must always be French, even though people seem to think it exists in all countries). Nobody ever thinks of Spanish cava or Italian spumante when discussing sparkling wine.
When demonstrating that you can pick the perfect wine to pair with your meal, it's always Bordeaux or Chianti.
Red or white. The most common red wine is probably Merlot, while the most famous white wine (as well as arguably the most famous wine in the world) is Chardonnay. If you're a Californian, you might mention Zinfandel and White Zinfandel, respectively.
Harold Ross, founder of The New Yorker magazine, would write "Who he?" on the copy whenever one of his writers used a name without explaining who the person was. He said that there were only two names you can assume everybody knows: Sherlock Holmes and Harry Houdini.
In this article, a teacher of English at a 'college of last resort' mentions that the only movie he can count on every one of his students being familiar with is The Wizard of Oz.
The only operating system is Windows, or Mac OS X. Go a bit further and you'll find GNU, though people will call it "Linux" and "open source". Even within that community, other historical and important operating systems (Genera, TENEX, ITS, WAITS) are forgotten in favor of UNIX. Which is hilariously wrong, since Linux is an OS kernel, and very few run GNU/HURD (the actual GNU kernel). For that matter, did you forget VMS? CP/M? Or the BSDs? Given that ITS was limited to PDP-6 and PDP-10 computers in MIT, it's not surprising that it's largely forgotten. Unix could and does run on a greater variety of systems than the Lisp machines for Genera or the mainframe-class PDP machines that TENEX, ITS and WAITS could run on. Also, you can add Multics and OS/360 to important historical operating systems that are forgotten within most communities.
The only way to crack into a computer is by guessing the password. Buffer overflows and SQL injections don't exist.
The only nuclear meltdown ever was Chernobyl. Despite this, it is still used to argue against nuclear power, because its infamy means everyone assumes a ton of people died all at once.
In the new tens, Fukushima equalled nuclear power plant failure.
To the average American, the only hurricanes to have ever happened were Katrina, Sandy, and whatever hurricanes directly affected them. For example, to somebody who lives near New York City, there was Katrina, Sandy, Irene, possibly Floyd, and that's it. Some people may remember Isaac, but that was only because it pushed the Republican National Convention back a day.
As far as typhoons are concerned, the only widely known one outside of East Asian countries is 2013's Typhoon Haiyan. While other typhoons like Bopha and Washi have also been really bad to the Philippines, Haiyan's record breaking intensity gave it worldwide attention and lead to major humanitarian response comparable to that of Katrina and Sandy.
The only earthquake in history was the one in Haiti.
Or, if you know that tsunamis come from earthquakes, you can add the Indian Ocean and Japan earthquakes.
Or that one in San Francisco? A long time ago? (1906 to be precise)
Loma Prieta 1989 (the World Series one) and Oakland 1994 might be mentioned, especially in works set in that area.
Possibly the one along the New Madrid fault line in 1812, but only if you're in the American Midwest.
The only volcanoes to have erupted are Mount Saint Helens and possibly Vesuvius.
The one volcano in Iceland that no one is (or ever will be) able to pronounce or spell correctly.
The Pelé Mountain in La Réunion. Because a whole city being wiped out in relatively-modern times is scary.
Krakatoa, which is west of Java.
It may be acknowledged that there are active volcanoes in Hawaii, but their individual names probably won't be mentioned.
For a while in the 90s, they trusted people to be familiar with Mount Pinatubo, but not so much anymore.
All pistols are either Glocks or "Colt .45s" , all shotguns are just "shotguns", all submachine guns are Uzis, all rifles are AK-47s, all mounted machine guns are either miniguns or ".50 cals", and all rocket launchers are "Bazookas". This even happens with people who do know a thing or two about guns - any M4 seen without the distinctive carry handle will be mistaken as an HK416, for instance.
The only school shootings to ever happen were Columbine, Virginia Tech, and Sandy Hook. Teenage shootings also apparently began in the late 1990s; no one remembers, say, the McDonald's massacre in San Ysidro, California, in 1984.
Most people know that not all roses are red, and are aware of white, pink, orange, and other varieties. But few realize that the archetypal rose form, with a whorl of petals that completely surround the interior part, is found among just a couple varieties, most notably the Hybrid Tea. Of the hundreds of rose species and cultivars that exist, nearly all look like "standard" flowers with open petals, and not like a "real rose."
Martial arts? You'll be hard-pressed to find people who know that it isn't just East Asian stuff or that the West has more than, say, boxing, wrestling, maybe krav maga... and even for the "famous" East Asian styles, most will just say "karate" or "kung fu", neglecting that these are broad categories with sub-styles that can vary quite drastically from one to another, such as the acrobatic-and-kick-centric changquan vs the close-in wing chun. Mixed Martial Arts has only slightly broadened the pool, partly because so few of the more obscure styles' practitioners make it big.
Cryptids in fiction will usually be Bigfoot, Yeti, the Loch Ness monster, and Chupacabra.
The card game Magic: The Gathering does this as well. They tend to use obscure but real mythical creatures, and the original sets, before the storyline became coherent and unique to the sets, would borrow liberally from odd sources.
Dennis Miller is famous for constantly bringing up obscure references, so much so that a website was created to decipher his comments on Monday Night Football for the average football fan.
Patton Oswalt likes to lampshade the obscure references in his stand-up, by effecting an even nerdier voice than usual, and mentioning something even more obscure.
David Mitchell argues against using small reference pools in this video, pointing out that many people, especially teenagers, are more likely to just Google the reference than to feel excluded for not getting it.
Neil Gaiman's Sandman references a great deal. For example, the second volume mentions Parliament's War, Fiddler's Green, etc.
Alan Moore and Kevin O' Neill's The League of Extraordinary Gentlemen is definitely a subversion. Sure, three of the original five league members are well known, but the two most important include the fairly obscure (and frequently misspelled) Allan Quatermain and a lesser known character from the novel Dracula. Beyond the League, the references get incredibly obscure.
The Black Dossier is nye literature code without some sort of cypher key to understand what he's talking about.
By the time of Century, the first issue its really light on this. But the second issue, being set on 1969, with a lot of series and film characters on the background and as characters... it's reference porn all the way.
They Might Be Giants have tried to rectify the situation singing the praises of Belgian painter James Ensor and the sorely underrated President James K. Polk, among others.
The 1975 Alice Cooper song "Department of Youth" does a bit of name-dropping, with Donny Osmond and Dwight D. Eisenhower both mentioned (Eisenhower undoubtedly familiar to most grade-school kids, and the Osmonds fairly commonly known), but also Protestant preacher (and former baseball player) Billy Sunday and short-story writer Damon Runyon, neither of whom most kids are likely to know. Lampshaded within the song when Alice goes "And we never hoid'a..."
Dykes To Watch Out For is festooned with literary, cultural, and historical allusions of all kinds (not solely LGBT culture, either).
Linus Van Pelt of Peanuts was fond of quoting Bible passages, often from fairly obscure books of both the Old and New Testaments. (And there is his immortal quoting of the Gospel of Luke in A Charlie Brown Christmas, but that had always been well-known to Christians.) And cartoonist Charles Schulz, a big sports fan, frequently mentioned famous athletes of the day, most of whom are all but forgotten today (French-Canadian hockey player Maurice Richard, for instance).
Calvin and Hobbes usually tried to steer clear of cultural references, but Calvin once compared the experience of walking through the snowy woods to Doctor Zhivago (an Academy Award-winning movie, to be sure, but one that most people have not seen since the 1960s). Another strip had Calvin waxing sarcastic about middle-aged pop stars endorsing soft drinks; this was fairly common in the early '90s (Ray Charles, Elton John), but many current viewers may not remember those commercials. Hobbes also once called Calvin out for misspelling the word "Weltanschaung."
Lasagna was not widely known west of the Hudson River or to non-Italian-Americans until it was revealed to be Garfield's favorite food. One strip even had Jon Arbuckle name-dropping various Italian cheeses as he prepared Garfield's meal: ricotta, mozzarella, parmesan (parmagiana in Italian).
Pythagoras, the ancient Greek mathematical theorist, is pretty well known to some Baby Boomers who remember his appearance in the Classic Disney ShortDonald Duck in Mathmagic Land. And they might also recall from that cartoon that the pentagram was originally the symbol of the Pythagorean secret society, nota sign of Satan.
BBC Radio show Round Britain Quiz is almost an inversion of this trope. It's a highbrow panel game for some very well-read intellectuals, except when it comes to anything that's recent, science-/engineering-based, or American. Then it switches to Huge Reference Pools — some people who know everything about classical literature or classical music (to take some recent examples) are clueless on questions about Elton John or Pink Floyd, or don't know which city is 'Motown'.
Tales of Symphonia has the angel Remiel, a somewhat obscure apocryphal angel, appropriately responsible for sending visions and prophecy. Some sources also make him responsible for those who will be resurrected. Both are appropriate for his place within the early game journey of rebirth.
While not the SMALLEST reference pool...in The Secret World, they mention Vivaldi as a composer.
Thanks partly to the influence of Gary Larson's The Far Side, many Dada Comics avert this trope, sometimes bordering on Viewers Are Geniuses. One instance in which this trope caught up was a panel in which one cowboy offered another a latte. In the days before Starbucks, many audience members were convinced that "latte" meant gay sex.
The names of The Order of the Stick books often reference works of literature, at least one of which is well outside the norm: War and XPs (Tolstoy's War and Peace), Start of Darkness (Conrad's Heart of Darkness) and On the Origins of PCs (Darwin's On the Origin of Species) Strips have also referenced the novel Dune, the musical Meet Me in St. Louis, and hinged several key character moments on a game of Go.
Irregular Webcomic! lives on averting this trope. Obscure mathematical jokes abound. Luckily for the majority of his readers, the extensive annotations underneath each strip explain the mathematical or scientific principle in question, often a whole lot better than your math teacher or textbook will. Extensive and accurate historical and literary jokes are also common. Irregular Webcomic doesn't sacrifice humor for "get out of my head" moments