Going Postal

"...this button-down, Oxford-cloth psycho might just snap, and then stalk from office to office with an Armalite AR-10 carbine gas-powered semi-automatic weapon, pumping round after round into colleagues and co-workers. This might be someone you've known for years. Someone very, very close to you. "

- Narrator, Fight Club

Some jobs are bad enough to knock a guy off his rocker. If one more person comes by and tells them to put the new TPS cover on the TPS report, they will go on a murderous rampage.

Real Life has more premeditated mayhem. In TV Land, the worker snaps on the spot and becomes an Improbable Weapon User, wielding something work-related, like a boxcutter, letter opener or something hefty to bludgeon with.

Named after a series of incidents involving U.S. Postal Service workers going on killing sprees that has henceforth become a part of popular culture.

While Going Postal is strictly a work-related massacre caused by a disgruntled employee, it may involve elements of a Berserk Button, a Rant Inducing Slight, Beware the Nice Ones, Selective Enforcement or a combination of the four.

For the Discworld novel, see Going Postal

Anime and Manga

 * The Puella Magi Madoka Magica doujin "I'm working at a mahou shoujo recruitment company, but I think I may be at my limit" has going on one of these near the end..

Comics

 * Judge Dredd: A lot of people suffer from this. It is known as Future Shock or Going Futsie. Interesting in that it is treated as a medical condition, rather than a crime.
 * The comic Irredeemable is the story of the day a Superman Captain Ersatz goes entirely and globally postal.

Film

 * Demon Knight. Wally. He was going to blow up the post office for the hooker he loved.
 * Falling Down. However, it is subverted by Det. Pendergast who faces much the same frustrations Bill Foster does, but handles them with reasonably civilized maturity and empathy. Furthermore, when the two characters meet at the climax at the film, Pendergast cuts down Foster's whining about being deceived by noting that everyone endures that problem, but that is no excuse for the several violent crimes Foster has committed that day.
 * To be fair, Foster only intentionally kills one person (A Neo-Nazi) and rarely hurts anyone else, and the film is very sympathetic to his perception of the world and how it is formed.
 * The main characters in Office Space joke about doing this early in the film, in order to establish just how terrible their jobs are.
 * Fight Club: The Narrator threatens his boss that this might be the consequence if he pushes too much when his boss discovers the photocopied "Rules of Fight Club".
 * Jumanji: when Van Pelt goes to the gun shop, the salesman's reply is "You're not a postal worker, are you?"
 * Jingle All the Way has Sinbad's character, who even had a spare homemade bombs package.
 * This surprisingly never occurs in the horror film The Mailman. The villain is a murderer, though not one of this type.

Live Action TV

 * One episode of Criminal Minds dealt with a workplace killer willing to do anything to avenge himself on the pharmaceutical company that (from his perspective) had abused him for years.
 * One of the group reaps in Dead Like Me involves this scenario. We don't see the actual shooting, and it (somewhat surprisingly, for this show) isn't played for laughs.

Music

 * The song The Night Santa Went Crazy, by Weird Al Yankovic, pretty much epitomizes this trope with a lovable childhood character.

Tabletop Games

 * The Illuminati New World Order "Post Office" card has a heavily-armed postman blazing away with a machine-gun.
 * Feng Shui has the 'Consumer On The Brink' character type, for players who want to play one of these in an action-movie setting.

Video Games

 * Fury Officer. Just...Fury Officer.
 * The videogame titled Postal, and its sequel. It's basically The Sims meets Grand Theft Auto.
 * Or to be more precise, Anal Cunt in video game form.
 * Boyd Cooper from Psychonauts both parodies and plays the trope straight, being a man who burns down the department store of his former security-guard job with molotov cocktails made out of milk bottles. His mental condition.
 * The Courier in Fallout New Vegas, if you so choose, can turn their journey across the Mojave into this.

Western Animation

 * Rocko's Modern Life has a postman revealing he was laid off and feeling disgruntled. The other passengers quickly vacate the car... only for him to swing around as he wanted space.
 * An episode of "Justice Friends" briefly features a Joker-like villain named Disgruntled Postman, who robs a post office to steal a single postage stamp to mail a bomb to the US President.