Usually featured in comedy works, this is any very, very, very long limousine belonging to some rich jerkass. Often used as a (no pun intended) Overly-Long Gag when a good portion of a scene is reserved for watching a limo take a lifetime to pull over. Of course, the main character will land inside (usually more or less forcefully) at least once. Sometimes the absurdly long vehicle will have nonsensical features like a hot-tub or a bowling alley attached.
And don't try to ask whether this thing is street legal or how it can make turns at corners; you would be missing the joke.
The animated opening of The Return of The Pink Panther has the Pink Panther arrive at a movie theatre in a pink limo with an incredibly long hood... and a tiny passenger compartment and open driver's section.
Spaceballs has a variation which does this gag with a spaceship.
Our Dumb Century from The Onion includes an article parodying ginormous cars of the 1950s. The Cadillac Dreadnought rolls on eight wheels, seats 24 people, and has three-foot-tall tail-fins, a basement, a dashboard-mounted martini mixer, and an optional three-season patio.
An aside in Solo Command mentions the existence of several luxury airspeeder limousines, spotted near a major corporation's executive entrance. (And used as evidence that it's probably not where the secret off-the-books project is located.) The vehicles aren't described in depth, but one of the Wraiths claims they were big enough to fit their own swimming pools.
Live Action TV
One episode of The Suite Life of Zack and Cody had London mentioning that she has a fleet of limousines so long that they can't turn corners. If she is traveling a route that goes around corners she needs to get out of one limo and into another.
Three were built as part of a Top Gear Challenge; of special note is Clarkson's, built from a tiny Fiat Panda and retaining the donor car's two-door configuration requiring passengers to commute within the car on a The Great Escape-tunnel-style cart, along with being so long it was no-longer road legal. In the final section of the challenge, Clarkson's limo had to be shortened so he could legally drive it in London, which lead to it breaking in half along the seam. Undeterred, Clarkson simply used the front half of his Panda, courtesy of front-wheel drive, to deliver his passenger.
Parks and Recreation: When Tom Haverford started his media company, he bought such a limo, with a hot tub in the back. It was this sort of business decision that caused his company to go belly-up quickly.
Phil Collins is seen relaxing in the hot tub on the back of a limo in "Take Me Home." It might be the "Worlds Longest Limousine"; we only ever see the back of it, but very few limousines have hot tubs on them.
The intro in Fiendish Freddy's Big Top O'Fun has the creditor arrive in one to deliver the notice that the $1,000,000 is due at midnight. After the limo drives off, the titular villain arrives in his small clown car.
Mother 3 has a private limo that Porky uses to pick up Lucas and his gang to bring them to New Pork City. It's sized fairly appropriately on the outside, but on the inside...
In the browser "card" game Urban Rivals, the opponent's card gets run over by such a limousine ( and peed on by a chihuaua) whenever you win by a large margin with a member of the Uppers.
There's one in the intro of Leisure Suit Larry 6, with a swimming pool and helicopter pad and tennis court, and takes forever to pass the screen.
Done in a lot of Looney Tunes shorts. In the Bugs Bunny short Oily Hare, the limo of the antagonist oil baron is shown to be so long that when he calls his driver from the back, he has to wait for an operator to patch him though because it's a "long distance" call.
Tex Avery shorts. A favorite gag would be the limo bending around corners to conform to the street.
Also done once or twice in The Flintstones. Like the above Looney Tunes example, a secretary or switchboard operator at the halfway point of the limousine would be used to reinforce the gag.
Once lampshaded by Skippy and Slappy Squirrel in Animaniacs.
Pinky Fox from Rock-A-Doodle drives a large, pink limo with twelve wheels. Toward the end of the film, when Edmund, Patou, Peepers, and Snipes attempt to get Chanticleer back to their farm to stop the villainous owl, they actually all steal Pinky's limo before Peepers gets them all to escape using another vehicle they all stole: Pinky's helicopter.
An episode of The Simpsons had a rapper's limo that had a wax museum in its basement.
The Tom and Jerry episode "Blue Cat Blues" has Tom competing with a rich cat for a kitty's heart. He eventually pulls up to his love interest's house in an old, broken-down car, only to be driven over by his competitor's limousine. It takes nearly 10 seconds before the front half of the whole thing drives into view (the driver's seat is in the middle), and another 8 before the back half drives out of view.
This was a recurring element of the Powerpuff Girls show. An enormous white limousine that is several windows long and takes a few seconds to cross the whole screen is always the Mayor's ride of choice in times of leisure. He rides in the back.
Montana Max from Tiny Toon Adventures has one of these with a built-in swimming pool, as seen in the cartoon, "Buster's Guide to Part-Time Jobs" from the episode, "Career Oppor-toon-ities."
The world's longest limousine is in the page image. This one hundred foot (30.5 m) long, twenty-six wheeled monster includes a hot tub and a swimming pool, and is mostly used in film productions and exhibitions. Imagine trying to parallel park this thing...