->'''Soujirou:''' Oh, back then, Bison was dressed up as Mike Tyson. Pretty cool.\\
'''Konata:''' Who's Mike Tyson?\\
''[later that day]''\\
'''Soujirou:''' Today, I felt the generation gap in a deep and very personal way.
-->-- ''Manga/LuckyStar'' Manga vol. 6

[[ItWasHisSled What was whose sled?]]

This is a subversion of PopCulturalOsmosis. When used in-universe, it's usually as a means of showing the difference between people from two different groups (usually generations) in which a character from Group A makes a pop culture reference (or mentions a famous person or movie or work) and one of four things happens:

# "Who's X?" -- The person from Group B doesn't get it at all because of a failure of PopCulturalOsmosis. This seems to be the most common.
# "Oh, X! He was in Y, right!" -- The person from Group B ''gets it wrong'' because of a failure of PopCulturalOsmosis (and he's guessing).
# "Wait, Y was based on a real X?" -- The person from Group B gets it wrong because of a ''clash'' of PopCulturalOsmosis, and he's [[TheWeirdAlEffect referencing something that referenced the original]], [[LostInImitation referenced a reference]] [[OlderThanTheyThink of the original, etc.]]
# "Impressive, you know X... oh, you don't" -- The person from Group B gets it wrong because of a clash of PopCulturalOsmosis, when person A is referencing something more recent (the reverse of 3).

This can happen because the person from Group B:

* A) is a bumpkin or is otherwise cut off from modern pop culture;
* B) is an outsider of the clique or subculture or is an immigrant or [[FunnyForeigner foreigner]];
* C) is old-fashioned and not knowledgeable of current popular culture;
* D) [[BeforeMyTime is young]] and [[IveHeardOfThatWhatIsIt the bit of pop culture]] is (relatively) old;
* E) is [[InTheOriginalKlingon amusingly]] [[FishOutOfTemporalWater displaced]] from the time of origin;
* F) simply is not familiar with a genre or a work;
* G) the work itself is [[FanMyopia thought to be so popular]] that all who know it think it will be passed on through PopCulturalOsmosis -- with the result that it ''isn't''.
* H) just is not interested in pop culture.

Note that AF can go both ways (for example, someone too old to know Music/BritneySpears or The Music/BackstreetBoys may have fond memories of ''Series/ILoveLucy'' or Music/HermansHermits), and G is the natural conclusion of PopCulturalOsmosis, when even AllThereIsToKnowAboutTheCryingGame is forgotten (along with ''Film/TheCryingGame'' itself) except for the [[TropeNamers trope name]] itself, rendered a NonIndicativeName.

This, by the way, is the reason character-named tropes are often renamed[[note]]Mostly. Part of it is because people, apparently thinking more potholes automatically makes a better example, will all too often shoehorn in links to tropes that have absolutely nothing to do with the example in question, other than that the example includes that trope's namesake.[[/note]]. For example, if you're not familiar with original Literature/SherlockHolmes tales, you won't know who InspectorLestrade is; if not well-read in 19th-century French literature (or [[AllMusicalsAreAdaptations Broadway musicals]]), InspectorJavert may be unknown to you.

With the advent of cable television, the Internet, and more things to do in less time, this is becoming more and more TruthInTelevision. Most everyone in the US watched ''Series/ILoveLucy'' because it was one of three television choices; not everyone watched ''Series/AmericanIdol'' because it was one of a thousand television choices (and hundreds of thousands of entertainment choices).

One of the many, many reasons for Administrivia/NotSelfExplanatory.

Compare SeinfeldIsUnfunny, AdaptationDisplacement, ForgottenTrope, ItsBeenDone, FleetingDemographicRule, RecognitionFailure, PopCultureIsolation, InformedRealLifeFame, LampshadedTheObscureReference, BeforeMyTime, and TechnologicallyBlindElders.

Contrast: ItWasHisSled, AllThereIsToKnowAboutTheCryingGame, and especially PopCulturalOsmosis.

* PCOFailure/Type1
* PCOFailure/Type2
* PCOFailure/Type3
* PCOFailure/Type4

!!Other Examples:

* During a flashback in ''Literature/TheDaVinciCode'', Robert Langdon is explaining to his editor about the real nature of the Holy Grail. The editor asks why he's never heard of it and Langdon answers that the cover-up "is backed up by [[Literature/TheBible the world's biggest best-seller]]". The editor immediately expresses surprise that ''Literature/HarryPotter'' talks about the Holy Grail.
* Invoked in the ''Literature/SixteenThirtyTwo''-series: Two time-travelling spies identify each others by the code names [[Franchise/StarTrek "Romulus" and "Vulcan"]]. The idea is that, since American pop culture hasn't penetrated the public consciousness of the 17th century, anyone in a position to recognize the names will assume that Romulus's counterpart is Remus.

[[folder:Web Original]]
* The [[http://knowyourmeme.com/memes/musically-oblivious-8th-grader Musically Oblivious 8th Grader]] {{meme|ticMutation}} uses various types.
* ''WebVideo/EndTimes'' plays with this a lot.
** Kimber is constantly missing the other survivors' pop culture references. Twelve years later the Archivist doesn't get them either, probably because 1) she was maybe eight back when TV or internet was a thing and 2) [[spoiler:she was at least partially brainwashed by a military dictatorship and spent most of her teen years as an assassin]].
** [[WebVideo/VlogBrothers "Those brothers that Charlie likes? with the... cancer book?"]]
[[folder:Real Life]]
* This phenomenon is the bane of anyone who studies myths and folklore. In many cultures there were certain myths so prevalent that no one actually bothered recording them, as everyone assumed everyone else already knew it. Then those cultures died off or changed, leaving many myths with references to others we don't actually know because there were no records made and people stopped learning them as they became less important.