Derailed for Details

Describe Derailed for Details here.

--OK. A character is trying to...

What's his name?

--Uh, Bob. Bob is trying to tell a story...

Which story?

--It doesn't matter! Shut up and let me finish! Ahem. Bob is trying to tell a story or joke, or ask a hypothetical or rhetorical question. He's interrupted constantly by requests for unnecessary extraneous details, quickly derailing the story into a Shaggy Dog Story or a Metaphorgotten. Common culprits are the Constantly Curious, the missing-the-point Cloudcuckoolander or the Mouthy Kid who's just trying to get on his nerves. Alternatively a self-conscious joke teller might do this to himself, adding unnecessary detail or going back and changing things.

AKA The Trope Where A Guy Starts Telling A Story Wait It Doesn't Have To Be A Guy Or A Story Either Really It Could Be A Joke Or A Speech But Anyway Where Was I...

Compare Derailed Fairy Tale, where the listener insists on adding his own details in; Disorganized Outline Speech, where the speaker doesn't really know what point he's trying to make in the first place, and Metaphorgotten, where unnecessary deviation sends an analogy off track.

Anime and Manga

 * In Student Council's Discretion, a rather basic math problem gets derailed in this way.

Film
"Brian: There was this man, and he had two servants. Arthur: What were they called? Brian: What? Arthur: What were their names? Brian: I don't know. And he gave them some talents. Eddie: You don't know?! Brian: Well, it doesn't matter! Arthur: He doesn't know what they were called! Brian: Oh, they were called 'Simon' and 'Adrian'. Now? Arthur: Oh! You said you didn't know! Brian: It really doesn't matter. The point is there were these two servants? Arthur: He's making it up as he goes along!"
 * In the Disney Channel Original Movie Pixel Perfect, the computerized character interrupts her creator's description of what falling in love feels like with questions like this.
 * In Monty Python's Life of Brian, telling the Parable of the Talents (Matthew 25):


 * In fact, the Pythons loved this kind of gag. Just in the Dennis Moore sketch John Cleese got lost in discussions about his target practice, British botany, European history, human anatomy and Not Actually the Ultimate Question while trying to rob some nobles.
 * In the famous opening scene of Monty Python and the Holy Grail, King Arthur's attempt to summon the Lord of the local castle derails into a discussion of how exactly King Arthur acquired a coconut shell in Medieval England, and ends with an argument over the migratory patterns of swallows.
 * Also from the Pythons, or at least Michael Palin, John Cleese, and Graham Chapman, comes How To Irritate People. In the show, which is a collection of sketches like Monty Python's Flying Circus, a man tries to tell his employer, who is visiting for tea, a joke he heard. Actually his wife wants him to tell it, and she keeps interrupting him to input unimportant details.
 * Subverted in Phenomenon. Somebody asks John Travolta's character how old a person would be now if they were born on the 5th of March 1987 (or was it the 7th of July 1976? No, it was the 28th of October 1928...) Anyway, he asks a bunch of questions, the last one being "Where was he born?" The exasperated questioner asks what that has to do with it. "Well, if he were born in New York City he'd be..." and gives the age right down to the minute. He never does explain, though, how a person's gender affects their age.
 * In Blade Runner, Holden asks Leon to imagine a hypothetical situation where he's walking in the desert and finds a tortoise on its back, the idea being to evoke an emotional response in order to determine if Leon is really human. Leon misses the point entirely and wants to know which desert, why he's there, etc.
 * In Stand by Me, Vern likes Gordy's story about Lard-Ass but isn't quite happy until he knows whether there was an entry fee for the pie-eating contest.

Literature
"Kishon: "It doesn't matter which tunnel! For all I care, it could be the Schlesinger tunnel! Swiss: "The Schlesinger tunnel? Now that's funny! Ha-ha-ha...""
 * In Saki's short story "The Story-Teller," the story-teller is so successful with the children because of his ability to readily answer their irrelevant questions and incorporate them into the story.
 * In his "Corfu Trilogy", Gerald Durrell relates that this was the only way he was able to learn history. His tutor told him all about Lord Nelson's butterfly collection and the names of Hannibal's elephants.
 * In one of his stories, Ephraim Kishon tries to tell a joke to a Swiss gentleman, who then uses this trope. The dialogue ends like this:


 * At the end, Kishon is so frustrated and ashamed, he hangs himself with an indestructible Swiss tie.

Live-Action TV
""A leprechaun walks into a bar. Wait, you're not supposed to know it's a leprechaun yet...""
 * The Mighty B!: The main character was trying to tell a joke:

"Stephen Fry: Tell me about the 12 Frenchmen and the 12 mosquitoes... Dara O'Briain: Once upon a time, there were 12 Frenchmen, and they were called 'Appy, Sleepy... er, Silly, Billy... Fatty and... Furieux. They went- Phil Jupitus: That's six!
 * The story gets progressively worse from there.
 * The Abbott and Costello sketch Jonah and the Whale: Lou's trying to impress a pretty girl with a joke, but Bud keeps interrupting with demands for details.
 * On The Wire, Prez tries to set his class a Train Problem and they pester him for details that would be relevant to an actual journey (which station it's leaving from, what the purpose of this guy's trip is, etc.), but not to the basic maths problem he has in mind.
 * On The Office, when asked which five books he would want on a deserted island, Dwight is obviously thinking too hard about it and asks whether there is any firewood on the island or whether he lost his shoes before he got there.
 * Dwight loves this trope - when asked whether it is just for a man to steal a loaf of bread to feed his family, Dwight just adds his own details - the bread is poisoned, and the kids aren't even his.
 * QI: (not word for word, for obvious reasons...)

Dara: Oh, all right... Philippe, Michel, Aujourd-hui, Flambé, Bof and Zut-Alors. And they used to go around with these 12 mosquitoes, solving crimes-

Phil: What were their names?"


 * In How I Met Your Mother, when Ted wakes up with a strange girl in his bed and a pineapple on his nightstand everyone tries to figure out who the girl is and how Ted hooked up with her ... except for Marshall, who's fixated on getting details about the pineapple.

Radio

 * On Ricky Gervais's XFM show, Karl Pilkington's stories were very prone to this. It was an especial problem when it came to his "Rockbusters" clues, which Ricky would often interrupt to warn listeners that whatever detail Karl was trying to settle to his own satisfaction might be completely irrelevant to the actual answer.

Western Animation
"Bart: And then what happened? Marge: They had 30 sons and 30 daughters. Bart: What were their names?"
 * In a Grim Adventures of Billy and Mandy episode, a bookworm asks Billy a classic two-trains question. Billy... makes one of the trains blue, full of clowns named Carl and Larry, with a conductor named Tim who is a vegetarian but secretly sneaks bacon when no one is looking.
 * In an episode of The Simpsons that takes place before Lisa was born, Marge is telling Bart a typical prince-and-princess story before he goes to bed.

"Marlin: All right, I know one joke. Um, there's a mollusk, see? And he walks up to a sea, well he doesn't walk up, he swims up. Well, actually the mollusk isn't moving. He's in one place and then the sea cucumber, well they--I mixed up. There was a mollusk and a sea cucumber. None of them were walking, so forget that I-- Bob: Sheldon! Get out of Mr. Johansenn's yard, now!"
 * Played straight in Finding Nemo:

Real Life

 * Truth in Television: This is a favourite tactic of small children for irritating their parents, of course.
 * Any university class will have this happen.

But what about...

--Shut up!