ISophagus

The iSophagus is any instance where, by swallowing a musical device or instrument, the swallower no longer speaks but emits music. Sometimes the person who swallows said item can magically control what is coming out of his mouth. Barring that solution the person must inflict bodily harm to himself to "change the channel". Oddly enough all that is required to make no noise is to shut their mouth. It stays in the person until it is expelled by hiccoughing or coughing, or else forgotten.

Additionally, a character may receive radio transmissions on his or her dental fillings, often citing that the vibrations from the sound wave vibrate the skull and ear drum. However, this is based on the misconception that radio waves, a form of light, work in any way whatsoever like sound waves. They don't. It also only picks up one frequency, effectively giving the afflicted the ability to listen to one perfectly tuned radio station. Again, this is often brought on by some grievous injury to start or stop it, and to change the frequency.

Examples of ISophagus include:

Advertising

There is a pair of Italian commercials, the first showing a man trying to find his new tiny cellphone when it rings, realizing the sound is coming from his small dog. He picks it up, pokes it in the tummy and holds it to his ear, and says 'Hello?'. The second one shows the same dog blurring and buzzing across a coffee table back and forth. "Now with vibration!"
One cell phone commercial shows a man at the vet with his dog, the dog having swallowed his phone. However, the phone is still on, and he's being charged by the call (which the vet hears through the dog's stomach via a stethoscope). The man then snaps on a glove, saying "I'm going in!". Cut to the dog whimpering.

Comic Books

Lobo once swallowed a harmonica during a fistfight without noticing. His subsequent weezing and the dark spot that showed up on the x-ray chart ended up being mistaken for lungcancer and promptly Played for Laughs as a desperate Lobo tried to quit smoking.
In a Spirou and Fantasio album (Qrn pour Bretzelburg), the Marsupilami once swallowed a state of the art miniaturized radio transistor (it was the Seventies), which somehow ended up stuck in its nose and started working intermittently, initially startling Fantasio in thinking it could speak, then depriving him for sleep when it refused to shut up, before picking up a distress radio signal and starting the plot.

Film

Lilo & Stitch does a variation of this trope. Stitch doesn't swallow Lilo's record player. But if you put his claw on the record, it works as a needle, and if you open his mouth, he becomes a phonograph.
The first Charlie's Angels movie used dental fillings.
Charlie Chaplin's City Lights did this bit with a whistle.
A variant of this occurred in the Transformers movie, where Bumblebee's damaged vocal processors force him to communicate with radio clips.
Brutally done in Cabin Fever where at a party a guy playing a harmonica gets it shoved down his throat after getting smashed in the face with a guitar. Cue to falling to the ground gasping for air complete with harmonica sounds.
Played straight in The Three Stooges short Disorder in the Court. When the stooges are reenacting a musical performance during a trial, Curly slaps Moe on the back, causing him to swallow a kazoo. They then find that when they press on Moe's stomach they can hear the kazoo, and soon Curly and Larry begin to make Moe play "Ach Du Lieber Augustine" by pumping his arm and squeezing his stomach, before he coughs the kazoo up.
The satellite phone gets eaten by a Spinosaurus in Jurassic Park 3. The characters know they're in trouble when they hear the Nokia jingle.

Literature

Singenpoo, a series of Australian children's books about a cat so named because it ate a radio.
In the Discworld novel Soul Music, mention is made of a kid with a penny-whistle whom the Musician's Guild "dealt with" for playing unlicensed music, who now plays a chord whenever he hiccups.
The protagonist of Fat Men From Space by Daniel Pinkwater has a dental filling that can act as a radio receiver.
- The problem of changing stations is handwaved by him being able to do so using different pieces of metal as an antenna. The plot of the book gets kicked off when he tries using a chain-link fence as one huge antenna and picks up a transmission from the eponymous aliens.
There's a Paul Jennings short story that combines this with a little bit of Body Horror when a boy gets a haunted harmonica stuck in his mouth.

Live-Action TV

Something similar happened on Gilligan's Island, when Gilligan's fillings start picking up radio waves after he gets hit in the head with a coconut. (I swear, coconuts are like lightning on that show...)
There's that urban legend about Lucille Ball having a tooth filling which worked as a radio receiver. It was busted on MythBusters.
The Goodies did it with a foghorn in "Lighthouse Keeping Loonies".
- The Goodies also did a variation on this when they themselves ended up in the stomach of a preserved dinosaur and were forced to manipulate it's vocal cords to broadcast a plea for assistance.

"Send help! And if you can't send help, send a good ventriloquist!"

The Monty Python's Flying Circus sketch "A Man with a Tape Recorder up his Nose". Naturally followed by "A Man with a Tape Recorder up his Brother's Nose."

AND NOW, IN STEREO!

The Petes' mother in The Adventures of Pete and Pete could pick up Mexican radio stations from the plate in her head.
Done in Green Acres where a cow swallows the transistor radio right before one of the characters is listening in for his chance to win on a radio show. The station changes whenever the cow burps and Hilarity Ensues.
Eerie, Indiana had a variation: A boy who could hear the thoughts of the neighborhood dogs through his headgear.
A Get Smart episode had a country singer (guest star Carol Burnett) swallowing a KAOS radio receiver shaped like a martini olive. Siegfried abducts her and tries listening to the broadcast in her stomach, but her nervous hiccups end up trying his patience.
In one of The Muppet Show's At The Dance sketches, Gonzo asks a dancer if it's the monster who ate his harmonica. The monster responds with a musical note.

Music

From the Barenaked Ladies' song "Light Up My Room" (which earlier brought up that they live near a hydro-field):

There are luxuries we can't afford
But in our house we never get bored
We can dance to the radio station
That plays in our teeth

Oral Tradition, Folklore, Myths and Legends

An African folktale about why Cat hates Rat explains that Rat played on Cat's precious family drum. When Cat chased and cornered Rat, Rat threw the drum at Cat, who accidentally swallowed it. While Cat was at first distressed, he found that he could recreate the drum's unique sound of "purrum, purrum" by stroking on his stomach. This is why cats purr only when stroked, so the tale goes.

Theatre

The 1943 Cole Porter musical Something for the Boys, originally starring Ethel Merman, had the heroine picking up military radio signal with her fillings.

Web Comics

Sluggy Freelance: This strip makes it the Trope Namer. Interestingly, though, it averts the usual ending of such a sequence. Rather than being coughed or spit up by Torg, it—well, let's just say "The problem has passed."
- iPood. In the iPotty.

Western Animation

Tom and Jerry have several occasions of this happening.
- One occasion has Tom changing the station on the radio he swallowed every time he hiccoughs.
- In "Mouse Trouble" he accidently swallowed a robotic female mouse programmed only to say "Come up and see me sometime." It becomes a Running Gag throughout the rest of the short that every time Tom hiccups you hear the same female voice saying "Come up and see me sometime."
Invader Zim included an episode where a child had a toy placed in his throat that made cow noises.
The Tex Avery cartoon Bad Luck Blackie has the villain swallowing a whistle, and the whistle blasts every time he hiccups. The whistle summons the black cat, and with the black cat comes the bad luck, and with the bad luck comes large things falling from the sky to land on the dog.
In the Droopy cartoon "The Three Little Pups", the laconic dogcatcher wolf tries to catch the dogs by sucking them into an enormous soda straw, but instead swallows the tv they're watching. He lifts his shirt to see the live-action Western still playing through his stomach, and switches it off via a button on his pants, drawling "Doggone - I seen that one last week!"
The Simpsons has a bit where Santa's Little Helper eats the remote and changes the channel by barking.
- Also, Mr. Burns swallowed a cell phone, apparently mistaking it for a lemon drop. It's set to vibrate.
SpongeBob SquarePants has this example when Patrick's head gets stuck through a trombone, essentially giving him a long brass neck.

Patrick: Whoever's the owner of the white sedan, you left your lights on.

- It's later played straight with Squidward when he accidentally swallows his clarinet reed.
A variation happens on The Jetsons: Astro swallows Elroy's anti-gravity toy and everybody believes Astro can fly.
In the third Mickey Mouse cartoon, Steamboat Willie, a goat eats Minnie's guitar and sheet music. Turning its tail like a crank caused it to play "Turkey in the Straw".
Sharon's braces in Braceface have been somehow electrified while being installed, and sometimes interact with metal or electronic environment around her—receiving radio, for instance, which manifests as Sharon hearing radio in her mouth.
One Disney cartoon short had Donald Duck come into possession of an ostrich. The ostrich swallows a radio and begins playing music.
- In another classic short, Pluto becomes obsessed with music. When he sits down in front of a radio, his butt hits the start lever on a gramaphone, and when his wagging tail touches the spinning disc, music comes out of his mouth.
- Another Disney short also features Pluto using his tail as the stylus for a record player, turning him into a speaker. The short ends with Pluto wowing the lady-dogs by playing a Frank Sinatra single.
Peter Griffin of Family Guy once swallowed his phone and dialed by punching himself in the gut. He was once put on hold and Lois told him to open his mouth so she could hear the song that was playing.
Told by Trent as an Urban Legend in the Daria episode "Legends of the Mall". The high school shop teacher (who eerily resembles Mr. Demartino...) grinds his teeth at night from the stress of dealing with his dumbass students. Once he's had the stumps pulled, he makes himself a set of metal dentures capable of biting through solid wood doors. Unfortunately, they pick up radio signals and periodically play "Girls Just Wanna Have Fun". Lampshaded when Daria and Jane point out how improbable it is... that it would always be the same song.
- Not really. Ever notice how if you never watch a certain show, when you ever do watch it, it's the same episode every time? Mr. Not-Demartino probably didn't listen to that station normally.
Clone High: In one episode, Joan of Arc's retainer picks up a Christian radio station, leading her to believe that she is finally hearing God like the original Joan of Arc.
The traffic cop from the Frosty the Snowman Christmas Special. His whistle may only be capable of one note, but he still swallowed it.
An episode of Dragon Tales was actually about Bluey accidentally swallowing his phone, and instead of pressing his abdomen to make it work, he actually uses his stomach muscles to move the rotary dial.
An animated short from Disney's House of Mouse was about Donald Duck accidentally swallowing a numeric keypad at an information kiosk.
- Another House of Mouse short actually ended with Louie the Mountain Lion accidentally swallowing Goofy's radio.
Adventure Time has an odd variation; Finn accidentally swallowed a computer, so when he tries to sing, he (almost) always sounds auto-tuned.
At the end of the Invader Zim episode "Dark Harvest", Zim replaces one of Dib's organs with a mooing can, with expected results.