Namesake Gag

In the real world, many things are named after the person who invented them or made them famous. The most often-cited example is a certain easy-to-prepare meal popularized by John Montagu, 4th Earl of Sandwich.

(And then there's Thomas Crapper, but that's another story, which we won't go into here.)

There are two easy ways of twisting this for comedic effect:
 * 1) Mention an invention that was named in this way, but get some detail wrong (for instance, by suggesting that John Montagu, Earl of Sandwich, is famous for inventing the montagu).
 * 2) Mention an invention that wasn't named this way, but claim that it was.

Not to be confused with gags refering to the book and Film of the Book entitled The Namesake, nor indeed jokes on the story's actual namesake

Film

 * In Mel Brooks' Robin Hood: Men in Tights, King Richard proclaims that, to remind everyone of Prince John's treachery, all toilets throughout England shall be called "Johns". (A modern American slang for toilet, for those that don't get the joke.)

Literature

 * Dave Barry uses this a lot, in one instance referring to Earl Tupper, who of course invented Earlware.
 * Also, the Marshall Plan, according to Barry, was named after General Marshall Plan.
 * Not to mention President Monroe Doctrine, "who wrote the Doctrine for which he is named."
 * In Good Omens, Anathema Device is descended from the man who invented the device. She has an entire rant about forgotten inventors, who also include Humphrey Gadget, Pieter Gizmo, Cyrus T. Doodad, and Ella Reader Widget.
 * And, Pulsifer's response (brought on by the rant) to hearing she's also a descendent of Agnes Nutter: "Let me guess, she invented the crazy person."
 * Discworld series:
 * In Feet of Clay there's a footnote about people with weapons named after them, and how they attract rumours that they were killed by their namesakes, beginning with the more-or-less historical Joseph Guillotin and ending with William Blunt-Instrument.
 * In Monstrous Regiment, there's an entire Running Gag about the tendency for famous military men (such as Wellington and Cardigan) to get either food or items of clothing named after them. Several of the characters have surnames that are either foods or items of clothing in our world, and by the end of the book, they all have completely different foods or items of clothing named after them. (Lieutenant Blouse, for instance, is commemorated in a type of glove.)
 * Soul Music mentions Sir Charles Lavatory, the Disc's equivalent to Thomas Crapper (and The Companion states his predecessor as head of the Plumbers' Guild was William Privy).
 * The Fools Guild Diary reveals that the founder of that guild was Jean-Paul Pune, inventor of the play on words.
 * According to the 1971 satire Bust-Up: The Uplifting Tale of Otto Titzling and the Development of the Bra by Wallace Reyburn, the bra was invented in 1912 by Otto Titzling, only to have his invention and fame stolen by the Frenchman Phillip de Brassiere. (The book inspired a song, which Bette Midler recorded in 1986 and reprised in the film Beaches. It was also recounted as fact in at least one edition of the board game Trivial Pursuit...)
 * In one of the Wayside School books, the kids are playing music and wonder how the triangle got its name. They decide it can't be named for its shape because "then the tamborine would have to be called a circle", so they reason it must have been invented by Joe Triangle.

Live Action TV
"Blackadder: Baldrick, go to the kitchen and make me something quick and simple to eat, would you? Two slices of bread with something in between. Baldrick: What, like Gerald Lord Sandwich had the other day? Blackadder: Yes, a few rounds of geralds."
 * Blackadder
 * "Ink and Incapability":

"Blackadder: May I present to you, the greatest breakthrough in travel since Sir Rodney Tricycle thought to himself, "I'm bored of walking. I think I'll invent something with three wheels and a bell, and name it after myself"..."
 * Blackadder Back and Forth:


 * There's an old Saturday Night Live sketch where a ball is attended by nobility with things named after them (Earl of Sandwich, Lord Worchestershire, Lord Salisbury) ...and Lord Douchebag.
 * In the Red Dwarf episode "Parallel Universe", Holly speaks of his ambition to have an invention named after him, like the Earl of Sandwich, Samuel Morse and... Plato, inventor of the plate.
 * In the Maid Marian and Her Merry Men episode "A Game Called John", the Sheriff invents a game that involves moving balls around on a cloth-covered table, and names it in honour of Prince John. After several varieties of hilarity ensue, including the Merry Men stealing all the green cloth to make uniforms, Prince John decides he doesn't want the game and gives it away, with all naming rights, to a random peasant -- whose name turns out to be Snooker.

Radio

 * A common joke in Bleak Expectations. The hero, Sir Philip Bin, made his first fortune by inventing a cylindrical receptacle for putting rubbish in -- although it takes several attempts before he thinks of naming it the "bin". (He then has to defend himself from a claim that he stole the idea from the American Hiram Trashcan.) The series also features Harry Biscuit, whose father invented the biscuit, and Dr Swim, who made the medical breakthrough that saved so many people from drowning.
 * An episode of I'm Sorry I Haven't a Clue mentions Coco Chanel, "who, of course, invented the popular bedtime drink". (The joke was later reprised in one of the show's spin-off books.)
 * A sketch on The Burkiss Way concerned the Duke of Wellington, who employed an artisan to invent a foodstuff to be named after him. The result was Beef Wellington - A raw cow wearing gumboots. After months in hiding and painful 18th century plastic surgery, the Duke re-emerges as the Earl of Sandwich, and employs the same artisan, who after months of experiments with hundreds of loaves of bread, produces... a single breadcrumb. Not very impressive on its own, but combine a large number of them together and you get... five hundred breadcrumbs threaded onto a piece of string.
 * Neil Malarkey's lecture on barcodes in an episode of The Unbelievable Truth claimed that they were invented by Baron Felix von Barcode, a contemporary of Michael Electricity and Sir William Shaving-Foam.

Theatre

 * In 'Dentity Crisis by Christopher Durang, Edith Fromage claims to be the inventor of cheese.

Theme Park

 * From the Jungle Cruise: "And on our left you'll see beautiful Schweitzer Falls, named after the famed explorer and philanthropist, Dr. Albert Falls."

Western Animation

 * The Simpsons' hometown, Springfield, is named after founder Jebediah Springfield. Nothing unusual about that. However, nearby Shelbyville is named after its founder, Shelbyville Manhattan.
 * The Deadly meteor shower is named after Martin Deadly.

Web Original

 * Mentioned as a gag in the Legendary Frog cartoon where Kerrigan decides to become an inventor and make millions. She says to her boyfriend, "Remember John from next door? John Velcro?"