This is Jimmy Kudo's favorite explanation for how his alter ego Conan Edogawa knows things that no six-year-old should. Of course, he's lying.
Even Ai Haibara, the local Kuudere, also pulled a Taught by Television Justification after she Character Filibuster about the hereditary nature of the Japanese upper class. Of course, she's also lying.
Codename: Sailor V, the manga that Sailor Moon is a sequel to, has Artemis being impressed with Minako knowing something about Greek Mythology until he finds out she learned it from a Video Game. He then creates the Sailor V Game to train her.
Subverted in JoJo's Bizarre Adventure, wherein Joseph discovers that watching Lawrence Of Arabia three times is not an effective means of learning how to ride camels. On the flip side, Jotaro claims to have picked up his impressive observational and deductive reasoning skills by watching entirely too much Columbo as a kid.
In Creature Tech, after Dr. Ong gets an alien symbiont attached to him, he falls asleep watching an old kung-fu film—while the symbiont stays awake for the entire thing. The next time Ong finds himself in a fight, the symbiont takes control of his body and uses the moves from the film to open a can of kung-fu whoopass.
In Hogyoku Ex Machina, Ishida lists off several medications for tuberculosis off the top of his head. When everyone turns and looks at him funny, he says he learned them from an episode of House.
Perhaps a more literal example: Jim Carrey's character in The Cable Guy is a man whose mother was a prostitute who was never around to teach him anything, and as a result he learned everything he ever knew from television in general (and sitcoms in particular). The plot revolves his brutally extreme measures to keep his life working exactly as he thinks it should be, following literal TV Tropes, even at the expense of others' safety and privacy.
Dae-Su Oh: The TV is both a clock and a calendar. It's your school, your home, your church, your friend... and your lover. But... my lover's song is too short.
An inversion forms the basic plot of Galaxy Quest: aliens intercepted the broadcast signal for a really cheesy sci-fi TV show, thought it was real, and based their (actually real) military on this "documentary." Also played straight when the fans save the day with their knowledge of the show.
In Chocolate, an autistic girl has a Disability Superpower allowing her to flawlessly imitate any movements she observes. She becomes an invincible fighter from watching action films.
Splash: Madison learns to speak English after watching television for a whole day.
At multiple points in Big Trouble, one of the two FBI agents comes up with totally obscure information about the topic at hand. When everyone else in the scene looks at him in amazement, he shrugs and says either "Discovery Channel" or "Travel Channel". Justified because it was implied that the agents spent a lot of time in hotel rooms with nothing else to do except watch television.
Bullet Proof Monk: the sidekick learned martial arts by working at a theater and imitating the moves he watched in old kung fu flicks.
In Days Of Thunder, Cole Trickle admits to learning how to drive stock cars from TV.
Harry Hogge: "What do you know about stock car racing?"
Cole Trickle: "Well... watched it on television, of course."
Harry Hogge: "You've seen it on television?"
Cole Trickle: "ESPN. The coverage is excellent. You'd be surprised at how much you can pick up."
Harry Hogge: "I'm sure I would."
In Explorers the aliens have learned English from watching Earth's television satellites.
There was a book where Rachel knows something about volcanoes. Everyone stares, and she explains that she saw an episode of The Magic School Bus. She was somewhat embarrassed about that.
And then there was the time Marco drove a tank... using his Playstation experience. And knew he could drive off a flatbed car onto the (raised) ground alongside the tracks because he saw it on the Discovery channel. Lampshaded by Tobias: "Ah. Video games and cable. How reassuring." To be fair, his skill at driving is about as good as you'd expect someone taught by video games to be.
"Do you just hate trash cans?!"
In the Maximum Ride series, the first book explains how the protagonists can function normally in a human society after spending their childhood being treated like animals - to the point of sleeping in dog crates - by... saying that they watched a lot of TV in the two years since they escaped the laboratory where they were imprisoned. Uh, okay.
In Friends, Joey knew how to deal with a jellyfish sting (you pee on it) because he saw it on the Discovery Channel. This is an example of such information being wrong (whether on the part of Discovery Channel or Friends). Urine actually makes jellyfish stings worse.
Nick in CSI: Crime Scene Investigation knew something obscure and was annoyed that everyone assumed he only knew it from TV, whereas if it had been Grissom, they'd have thought he'd read it in a book. Even though he actually had seen it on Discovery.
In the House episode "Frozen", Kal Penn's character explains his knowledge of Antarctic ice-breaking equipment this way.
There was an episode where J.D. diagnosed a patient with Necrotizing Fasciitis based on a documentary he'd seen the night before. Cox mocked him, but he turned out to be right.
In another episode, Cox gets annoyed with the new interns for getting their information from House. See the Real Life section.
Subverted hilariously in the Cousin Skeeter TV movie New Kids on the Planet, where Skeeter tries to show of his "Kung Fu Skills" from watching tons of martial films to aliens. The aliens then pulled an Indiana Jones, and just shot near him. Skeeter surrenders immediately.
However, Bobby did manage to fly a NASA rocket ship thanks to a flight simulator video game.
In an episode of Dirty Jobs, Mike Rowe rattled off some trivial knowledge about farm animals, then pointed to his temple and said "Discovery Channel." Clearly, even Discovery Channel hosts can learn from the Discovery Channel.
Keith Miller from EastEnders embodies this trope. This is a case of the actor adding a little of themselves to their character. David Spinx is well known to compete in Pub Quizzes at his local, so naturally his head will be filled with random knowledge.
In My Family, a Charity store owner identifies a highly valuable teddy bear because "we all watch Antiques road show".
In Masked Rider, Albee and Molly tell Dex to learn how to talk like a human from watching television- which he does all night. The trope ends up being subverted-Dex instead memorises tv commercials!
Rose on The Golden Girls stuns everyone by correctly answering a Trivial Pursuit question about Mozart's "Eine Kleine Nachtmusik." She explains that she learned it from watching Bugs Bunny cartoons.
Ned the piemaker from Pushing Daisies is capable of competently fending off a skilled swordsman due to his childhood desire to be a Jedi.
A character on Heroes actually has this as her power — anything she saw on TV, she would instantly be able to do perfectly.
Sawyer from LOST claimed that anyone who watches TV knows how to improvise a slow fuse with a cigarette.
One episode of The Big Bang Theory has Sheldon threaten Howard with a throwing star (Shuriken), claiming he had learned how to use it from watching movies.
Castle explains he can speak Chinese because of a TV show he used to love.
Travis Touchdown in No More Heroes learns new wrestling moves by watching old videos.
Subverted in Melonpool: at one point the crew encounter a giant space amoeba. At first they relax thinking Mayberry knows what to do, since he is a Star Trek fanatic and can simply do what the Enterprise crew did when they encountered such an amoeba in "The Immunity Syndrome"... however one of the comic's running gags is the fact that Mayberry has seen all episodes of the Original Series... EXCEPT "the one with the giant space amoeba" and is eternally prevented from doing so.
In Homestuck, Karkat's interest in romantic comedy films earns him some mockery from his friends, but also gives him insight into troll psychology and romance that none of his peers could match. When other trolls need advice regarding their love life, Karkat is almost invariably the one they go to.
Lisa claims that this is how she knows about hermit crabs' shells to a bunch of kids in one episode.
Bart hides from a Shelbyville gang in the tiger-handler area of the zoo (It Makes Sense in Context) and finds a note that the only way out (i.e. without any tigers) is door number 7, only the doors are labeled with roman numerals, which Bart doesn't know. Until he remembers the Rocky sequels and pieces it together just in time. The real joke there, though, was that they had studied roman numerals in his class, that same day (a.k.a. earlier in the episode), but he didn't pay attention.
Doctor Nick Riviera, Springfield's leading quack, tries to perform open heart surgery on Homer guided by a videotaped tv show. Of course, something went wrong when setting the recorder...
Bart was once caught shoplifting and Homer was disappointed Bart wouldn't have known better after watching Police Academy movies.
In one episode, the shrunken-down cast flies through Fry's nose. Dr. Zoidberg points out a nasal capillary they can fly through, and Hermes asks how he knew about that, as Zoidberg generally knows nothing of human anatomy. Zoidberg mentions his medical training, but admits that this he learned from a commercial for allergy medicine.
A variation of this is used in Duck Dodgers, "The Queen is Wild", wherein Dodgers claims to have "learned all [his] hard sciences from reading comic books". The scary thing: His idea worked.
During the episode "The Ci-Kat-A" on Swat Kats, Razor seemed to know exactly what the alien bug monster was going to eat and where it was going to go. When T-Bone asked him how he knew all that stuff, Razor replied: "Horror movies, where else?"
Averted in a episode of Pinky and the Brain, where the Brain realizes too late that Pinky had the answer to a TV trivia question he needs to win a game show, after he has already knocked Pinky out for being annoying. Which is, of course, a reference to The Honeymooners.
Played straight in another episode where the two find themselves on an alien ship. Pinky knows how to pilot it due to it being identical to the one shown in "The Z Files", which Brain had earlier berated Pinky for wasting time with.
In the storybook Time Out!, Timmy is able to answer a teeth-themed riddle thanks to his favorite episode of a TV show he watches.
In American Dad, Roger wants to become a police officer: "Do you know how many Police Academy movies I watched in preparation for this? NONE, because I knew it would only give me bad habits!"
When the Smiths are stranded in a desert. Stan uses their urine soaked clothing to wear on their heads because he saw it on Man Vs Wild. Shortly, their heads are freezing at night. Stan gets them to huddle together for warmth which he also saw on Man Vs Wild.
South Park: When Hell's Pass Hospital was understaffed, Chef was accepted as a replacement just because he once watched an episode of ER.
In an episode of The Flintstones, when Fred fakes an injury, the doctor diagnosing him has no idea what he's doing, admitting that he "saw a doctor do it on a TV show once."
"I got to hurry now."
"What is it, Doctor? An emergency?"
"What emergency? I got to go home and watch TV."
CPR was a fairly rare skill set and not commonly taught to the general public until emergency workers started seeing it being used in the 1970s by civilians (mostly wrongly, but they had the basic concept) with no training. They'd seen it being used, and knew what it was for, on Emergency!
Medicine students often learn a lot about diagnosing patients by watching House. To the show's credit, it raises awareness about rare conditions that are often under-diagnosed or missed by younger doctors who have no personal experience with that particular condition. The show has also helped raise Lupus awareness, which is good news for Lupus patients in general. The form of diagnosis that House employs is sound. Med students would learn to watch for little details, not to take everything a patient says at face value, and to consider symptoms that might not be seen as symptoms. All of this is a good thing if it helps prevent someone from being misdiagnosed.
Although some doctors blames the show (along with others like Grey's Anatomy) for making new doctors immediately jump to obscure and deadly diseases before ruling out the more obvious options first and spooking the patients. But a few good snarks from the attending doctor usually takes care of that.
One teaching doctor would record episodes of Casualty, label them by injury and use the make-up work to show his students what the injuries looked like.
From 1989 to 1996, Rescue 911 was responsible for having many lives saved by people who saw the show. In fact, the show aired two episodes, called "100 Lives Saved" and "200 Lives Saved," showcasing stories of people who saved lives thanks to what they saw on Rescue 911.
Episode 5 of Season 6 of Canada's Worst Driver had a guest appearance by a viewer who escaped a dangerous situation using the Swerve-and-Avoid technique taught on the show.
On at least one occasion, a elementary-school child has saved a friend by using the Heimlich Maneuver. Which they learned, it should be noted, by watching The Simpsons.
This is supposed to be the purpose of Baby Einstein videos. Although, at least one study showed that they had the opposite effect.