One Side of the Story

"Lisa: Wait, let me finish my sentence!

Homer: Never!"

- The Simpsons

One character jumps to the most obvious conclusion from what he or she has just observed about another character. The resulting argument then proceeds in a one-sided manner, so that the other side doesn't get to tell their side of the story (which is always the correct one). Expect to hear "'But...' 'No buts'" in there at some point.

May facilitate an Oops I Did It Again plot or result in Type A of Why Didn't You Just Say So?.

Compare with The Rashomon. See also You Know What You Did.

Comic Books

 * When Huey, Dewey and Louie first tried to join the Junior Woodchucks - according to a Don Rosa story, they were outright rejected for calling Elvira Duck "Grandma", as they usually do because the Senior Woodchucks assumed they were rude kids who call old ladies like that. One of the boys tried to explain but got a "No Buts" and only got allowed back when Elvira explained she's technically their great-grandmother.

Film

 * In The Sixth Sense, Her entire character (in other scenes as well, such as where ) changes based on that info.
 * Hitch. The title character's love interest Sara has a friend who slept with a guy who dumped her the morning after. On the way out the door, he makes an offhand comment, "Date doctor my ass." Sara makes it her mission to find the date doctor and expose him, blaming him for enabling the scumbag to use her friend.  The kicker?   And then Hitch takes her back.

Literature

 * Harry Potter: Sirius Black spent years in Azkaban Prison because everyone who didn't know Peter Pettigrew was a Death Eater assumed Sirius betrayed the Potters and killed Peter Pettigrew and several muggles. It was eventually revealed Peter faked his death and framed Sirius with everything.

Live Action TV

 * 8 Simple Rules...: John Ritter continuously berates one of his daughters for shoplifting. In reality, the friend she was shopping with did it.
 * Full House: D.J. was trying to take a beer can away from two boys at a school dance when her uncle Jesse catches her in the hallway and wrongfully accuses her, until the two boys who were drinking confess to Jesse and he apologizes to D.J. Slightly different in the respect that D.J. did get to tell her side of the story, but even after answering every one of Jesse's questions, he still didn't believe her and didn't even consider the possibility she was telling the truth.
 * El Chavo Del Ocho: Whenever Dona Florinda is sure Don Ramon hurt or tried to hurt her son, she'll certainly slap him and never allows him to explain. She's lucky he Wouldn't Hit a Girl.

Manga and Anime

 * Ranma 1/2 pretty much lives on this trope, with Akane barging in with fist flying and Ranma (social retard that he is) usually too tongue-tied to do more than stammer out a "Let me explain" before going sub-orbital. Maybe one time out of ten is the incident that draws Akane's ire actually Ranma's fault. (Although, to be fair, there's much less of that in the manga)
 * It's even Lampshaded at one point, where Akane asks why didn't Ranma just explain what was going on, and Ranma replies, "Have you ever listened to anything I say before you pummel me?"

Video Games

 * Guild Wars plays with this on multiple levels. The Charr in the first game are presented as an Always Chaotic Evil race of invading fire-worshiping hellcats who live to destroy and enslave, and like to eat their human prisoners, and that slaughtering and torturing the Charr is not at all a bad thing. Both the characters in-game and the players were lead to believe this was the truth. Cue Guild Wars 2 revealing that all that was only propaganda from the human kingdoms - the Charr are far more complex, never ate people, and the invasion was their struggle to reclaim their occupied homeland.

Western Animation

 * I Am Weasel: the Weasel berates I.R. Baboon for coming late for a motorcycle test. Turns out he forgot the brakes to the motorcycle, leading to wacky hijinks.
 * Mickey Mouse Works: Daisy's berating Donald Duck for (for example) dancing with her neighbor (the neighbor literally dragged Donald into it), while he's supposed to be building a brick wall at her house.
 * All Grown Up!, "Brother, Can You Spare The Time?": Dil appears on a talk show, "What's Your Tragedy?", about Tommy abandoning him upon winning an award in filmmaking, prompting booing and jeers from the audience when Tommy shows up to explain his side (basically, that it's not the case at all).
 * Rocket Power, "Race Across New Zealand": Ray Rocket won't stop flapping his yap on how his son Otto doesn't like to lose to hear out his daughter Reggie's own grievance: that she managed a tie in the previous race, and the only thing Ray cared for was Otto's loss.
 * Many Looney Tunes shorts operate multiple gags on this premise, most notoriously "Bugsy and Mugsy", where Bugs is able to convince Rocky the Gangster that his sidekick, Mugsy, is trying to kill him.
 * The first Shrek movie pulled off a two-sided version of this. Shrek half-overhears a conversation between Fiona and Donkey, but misses the most significant part: that Fiona turns into an ogre at night. The next day Shrek and Fiona both assume that Shrek heard the whole conversation and each jump to a false conclusion.
 * The Shrek conversation is skillfully crafted to become two separate scenes based on whether or not you know the piece of information; of course, the audience is aware of it at the time.
 * A variation of this takes place in How to Train Your Dragon (the film), when Hiccup tries to tell his father that he really can't kill a dragon. (He knows this to be so because he just had a golden opportunity to kill one, the Night Fury he later names Toothless, and couldn't bring himself to do it.) Stoick, his father, keeps brushing off his objections as fear and browbeats his son into agreeing to enter dragon training. Hiccup even lampshades the trope by noting that "This conversation is feeling very one-sided."
 * In the Sadie Hawkins dance episode of As Told by Ginger, Darren thinks Ginger is jealous because Courtney invited him to the dance while Ginger is going solo (Ginger's actually trying to tell him that Courtney meant to invite his older brother Will).

Manga and Anime

 * Almost every arc of Higurashi no Naku Koro ni runs on this trope.
 * In Full Metal Panic, Sousuke seems to have this going for him whenever anyone gets too direct about trying to convince him that someone has feelings for him. Many times, while they're in the process of trying to explain to him why someone is acting strange around him, he'll end up interrupting them before they get too direct, coming to his own outlandish conclusion as to the reason why. Most people just sigh and shake their head. This tends to happen the most in relation to Tessa.
 * In Tsukigasa, the facts everyone knows are that Azuma cut off Kuroe's arm and Kuroe ran away and joined a band of robbers. Everyone has their own idea of what actually happened and why it happened, many of which are misinformed because they are unwilling to just put it all out in the open. Eventually all the pieces are dragged out one by one and things get resolved but it takes awhile.

Western Animation

 * Hey Arnold!, "Arnold & Lila": Lila won't stop talking long enough to allow Arnold time to say he didn't write "Arnold and Lila" on some wall. Helga had scrawled "Lila" in place of you-know-who to hide her dirty laundry... only to create this other dirty laundry.
 * All Grown Up!, "It's Cupid, Stupid": Nicole won't stop being excited over Tommy long enough for Tommy to tell about Chuckie wanting to ask her out to a Valentine's dance (Imaginary Love Triangle).
 * Danny Phantom, "Splitting Images": Monster of the Week (not really a monster, but who cares?) Poindexter believes Danny to be a bully after Danny dealt Dash (an actual bully) some much-needed humiliation, and, yep, won't even let Danny explain himself. Once the initial confrontation is over, it's just taken for granted that Danny apparently was wrong, in an Anvilicious "With great power Comes Great Responsibility" Aesop. One that he seems to forget on several occasions and has even has to visually re-learn within the first Made for TV Movie.
 * A Charlie Brown Thanksgiving: Peppermint Patty invites herself to Charlie Brown's house for Thanksgiving dinner, not giving Charlie the chance to explain that he's going to his grandmother's for dinner.
 * She is eventually called out on it after Marcy asks her if Charlie Brown really did invite her, Franklin, and Marcy over for Thanksgiving Dinner, however.
 * This is the basic schtick of Foghorn Leghorn. He goes on and on without letting the other characters get a word in edgewise, then complains how they never listen to a word he says.