If there's anything parents know, it's how kids obsess over [[{{Toys}} the latest thing]], [[DeaderThanDisco then forget about it after a week or so]], hence why the TrendAesop exists.
* Any number of fad {{toys}}. TheEighties had Franchise/CabbagePatchKids, (which lasted through TheNineties and are making a valiant attempt at a resurgence), Toys/TeddyRuxpin, Toys/{{Simon}}, [[VideoGame/GameAndWatch pocket games that play only one game]] (such as ''VideoGame/PacMan'' or ''VideoGame/{{Centipede}}''), [[WesternAnimation/PoundPuppies1980s Pound Puppies]], the [[ComicStrip/{{Peanuts}} Snoopy snow cone maker]], and WesternAnimation/RainbowBrite (though those last three are making something of a comeback). In TheNineties, it was VideoGame/{{Tamagotchi}} [[note]] Tamagotchis are still fairly popular in UsefulNotes/{{Japan}}, though the ones made there nowadays are nearly InNameOnly. {{Virtual Pet|s}} games have also found an audience with fans of 1990s nostalgia.[[/note]], [[Series/SesameStreet Tickle-Me-Elmo]], Toys/BeanieBabies, [[AnyoneRememberPogs pogs]] ("tazos" in Mexico, Australia and other countries)... the list is ever-growing. Anyone who grew up at the time that any one of these were popular has probably witnessed the popularity arc go from "niche item that only a few people have heard of" to "waiting in line for half a day just to get one, then seeing people fight in the store over the remaining stock" to "finding a bunch of well-worn ones for 50 cents at Goodwill".
** For the old fogies in the crowd: [[CompanionCube Pet rocks]]. Mood rings. Lava lamps. (Although that last one has never quite gone entirely away, but is now mostly the venue of young kids and people of a certain age who buy them for either camp or nostalgia. A lava lamp seen in a movie or TV show is an indicator that [[TheStoner its owner]] smokes a ''lot'' of pot.)
** Once upon a time, any {{Fantasy}}, ScienceFiction, or ActionAdventure movie or TV series would get a short lived toyline. ''Film/PlanetOfTheApes'', ''Series/SixMillionDollarMan'', ''Film/LogansRun'', ''Franchise/StarWars'', ''Franchis/StarTrek'', ''Film/RaidersOfTheLostArk'', ''Series/{{Space 1999}}'', ''Franchise/BattlestarGalactica'', ''Series/BuckRogersInThe25thCentury'', ''Series/TheATeam'', ''Series/DukesOfHazzard'', ''Series/TheMunsters'', ''Series/TheAddamsFamily'', ''Film/SmokeyAndTheBandit'', ''Film/CannonballRun'', ''Series/{{CHiPs}}'', and ''Series/KnightRider'' all had toylines. Even seemingly unlikely candidates such as Creator/RalphBakshi's ''WesternAnimation/TheLordOfTheRings'', the R-rated ''Film/{{Alien}}'', ''Film/BladeRunner'', and ''Film/{{Rambo}}'' or even the PG-13–rated 1984 ''Film/{{Dune}}'' had toys produced. There was also TV tie-in toy merchandising with mainstream shows like ''Series/{{Bonanza}}'', ''Series/AllInTheFamily'', ''Series/WelcomeBackKotter'', ''Series/TheBradyBunch'' and ''Series/{{MASH}}''. Most of these are still collectible today. What is worth remembering at the time is that these toys were targeted toward children and not toward adult geeks. This makes it amazing that they created toy-lines based on films that children were not likely allowed to watch, such as the aforementioned R-rated films. Don't look for any toylines based on most of today's genre shows or films, there will definitely be no more tie-ins toy-lines for for UsefulNotes/PrimeTime {{UsefulNotes/television}} comedies. Today's trend is towards more naturalistic settings and characters in genre films and series, and a good number of them are strictly adult level and not suitable for viewing by children. At the very least, children may be bored by the lack of action. The current trend in genre shows is slow paced episodic stories that focus on characters and their relationships, so making action figures for such shows is somewhat absurd. In the rare occurrences that such toys are made today, an immediate backlash is inevitable, the toys (actually available at ToysRUs) based on ''BreakingBad'' being a perfect example. These toys were immediately pulled from the store shelves.
* Home chemistry sets and other science kits, thanks to a combination of perceived dangers to life and limb and the Wars on Terror and Drugs. The Gabriel and Skillcraft sets were highly acclaimed for being equipped with everything a budding young chemist needs: scaled-down chemical glassware (real Pyrex), apparatus, and a host of chemicals used by real chemists. As a bonus, you could order from their catalogs for even more items. However, due to [[MyLittlePanzer perceived safety concerns]] and fear of lawsuits from [[MoralGuardians angry parents]], [[ScrewedByTheLawyers test tubes and beakers are now plastic; there are no alcohol burners; chemicals are now mostly limited to vinegar, table salt, table sugar, and other "safe" household items that are expected to already be on hand, and experiments are limited to simple, boring reactions such as color changes]].\\
On top of that, there is a fear among police and various [[MoralGuardians public safety groups and advocates]] that chemistry sets can be used to manufacture explosives and methamphetamines. (''Series/BreakingBad'' has likely done little to help with the latter image.) Thanks to this, there have been a number of highly publicized police raids into the homes of what were nothing more than chemistry hobbyists, and suppliers became very leery about selling their products to anybody other than schools and laboratories. Some states, such as [[EverythingIsBigInTexas Texas]], have even gone as far as requiring a government permit for the possession of just chemistry glassware.
* Hobby telescopes: These are often sold in toy stores, department stores and novelty stores, and they are usually priced anywhere from $49.99 to $99.99. With a little research, any budding amateur astronomer will instantly realize that the only good telescope is a telescope that you purchase from a dedicated and reputable science vendor. They are more expensive but if one is serious about the hobby, it's worth the investment.
* [[MerchandiseDriven Cartoon/toy-line tie-ins:]] These are now considered strictly a relic of TheEighties. ''Franchise/{{Transformers}}'', ''Franchise/GIJoe'', ''Franchise/{{Voltron}}'', ''Franchise/MastersOfTheUniverse'', and many others had popular cartoon shows that were arguably just advertisements for the toylines. Strict government regulations against child-targeted commercial advertising saw the end of this sort of marketing. Today, toys based on these older franchises are targeted toward nostalgic adults and are priced accordingly. {{Transformers}}, however, seems to have survived and is still going strong.
* Any toys that resemble real-life firearms or weapons. Drug and/or gang wars of TheEighties and onward involved a lot of gun-play, and city kids who brandished realistic fake weapons risked being shot for real by criminals, police officers, or both. To safeguard kids, toy guns now are brightly colored (black is disappearing), usually have a tell-all orange tip barrel, represent no commonly available firearms, and can't be easily painted to resemble real guns -- they look more like {{fantasy}} / SciFi weapons. Also thanks to this law, the original toy of ''Franchise/{{Transformers}}/ Megatron'' cannot be reissued in the US. Usually, their appearance is also out of proportion with real guns so they can be spotted at first glance. Cap guns, meanwhile, have vanished due to the public's tendency to mistake their noise for real gunshots. {{Water guns|AndBalloons}} like [[Toys/NERFBrand Super Soakers]], however, are still very popular, largely because nobody could confuse them for real guns.
** The only "toy" guns still sold today that resemble real weapons are BB rifles, which get by on the GrandfatherClause (the Daisy Red Ryder BB gun was famously featured in ''Film/AChristmasStory'', after all), and Airsoft guns, which are often very expensive and marketed strictly to hobbyists and the like. And even in those cases, nearly half of all US states regulate their sale and use.
* Toy soldiers based on any historical war. Back in the days of WorldWarII, the US Military [[BlackAndWhiteMorality were undoubtedly the rough 'n' ready good guys fighting valiantly for liberty and justice against the evil]] UsefulNotes/NaziGermany regime. With the onset of TheVietnamWar and especially TheWarOnTerror, we began seeing more shades of gray, such as innocent people on "the other side" suffering as a result of the wars, the American Government making some objectively boneheaded decisions, and fathers who served in the wars either dying or coming home crippled. It more-or-less became clear that WarIsHell and ''not'' the kind of thing we want our kids glorifying.
** This can be seen easily with ''GIJoe.'' The original figures were explicitly designed as American infantrymen, but after Vietnam, the line shifted focus to adventure stories or battling absurd supervillains, largely jettisoning anything that could associated with an actual war. It's hard to imagine, for instance, Snake-Eyes in Afghanistan.
* Toys/{{Bratz}} dolls. When they first came out at the TurnOfTheMillennium, the fashion dolls were hugely popular in a way no prior Franchise/{{Barbie}} rival had ever been, and ''very'' controversial due to their "slutty" appearance for characters who were supposed to be teenagers. Now thanks to said controversy dying out, several failed retools and {{spinoff}}s, a lengthy hiatus due to legal issues, and the rise of doll lines such as Toys/MonsterHigh that feature LoadsAndLoadsOfCharacters with truly distinctive personalities and strong WorldBuilding, the Bratz franchise is struggling to stay afloat and is virtually dead. There's a good chance most toy-buying kids aren't aware the line still exists, or even ''existed''. A reboot of the line came along in 2015 but many, even former fans, doubt it will last long.
** Even Moxie Girlz, created by the same company to replace it, isn't doing too well and now exists mainly as a LighterAndSofter budget line.
* Sea Monkeys was one of those "hard to believe it was popular" fads. Inspired by ant farms, these were homegrown brine shrimp marketed as novelty aquarium pets, heavily marketed, especially in comic books starting in 1957. Unfortunately, the advertising was rather deceptive, showing humanoid animals that bore no real resemblance to the actual shrimp, and many buyers were disappointed by the dissimilarity and by the short lifespan of the animals, and the fad eventually died out. Although, Sea Monkeys had [[CrowningMomentOfAwesome one moment of glory]] in 1998, when astronaut John Glenn took some aboard Space Shuttle ''Discovery'' during mission STS-95. After nine days in space, they were returned to Earth, and hatched eight weeks later apparently unaffected by their travels.