Crush Parade

Alice has something that is very important with her that she is trusted to take care of. While walking along the street, Alice runs into Bob, who can't help but take notice of the precious item in Alice's possession and wishes to get a better look at it and hold it himself. After much protesting, Alice gives in and agrees to let Bob hold it "for just one second." Bob, however, is a klutz or an asshole. The second Bob is handed Alice's MacGuffin, it winds up falling into the street where it is immediately run over by an oncoming car.

But maybe it doesn't look so bad. Maybe there's small hope that what has been broken could be salvaged.

Just as Bob is about to suggest to Alice that it might not be so bad, another car comes by and runs over the MacGuffin again... and another... and then a truck!

Next, a marching band heard in the distance comes by and tramples over the crushed mess as they pass... followed by parade floats, a row of elephants, and army tanks.

By the time the steam rollers show up, you absolutely know for certain that Alice's item is completely wrecked.

Finally, something considerably smaller compared to what came before (such as a man on a tricycle or an old lady with a cane) runs the MacGuffin over one last time just to sprinkle one last pinch of salt in the emotional wounds.

Crush Parade is essentially an exaggerated form of Squashed Flat where an item that's either highly valued or greatly needed by a character that winds up falling into a street to be predictably crushed and flattened is Played for Laughs in an over-the-top, absurdly comedic fashion, usually at the expense of The Woobie or The Chew Toy.

When this happens to actual characters, this can be a more literal form of a Humiliation Conga or a variant of Rasputinian Death.

This is very common in Animation genres where a gag like this is more of an Acceptable Break From Reality.

Comic Books

 * One of the most letter-accurate examples was in the Don Martin story (published in the paperback Don Martin Steps Out!): a man declares to his wife that the anesthetic his dentist had just given him worked so well he was completely numb, and let his wife experiment with a head tap with a hammer - just as a safe drops from a high building onto his head. His tongue unfurls all the way across the street - just in time for a big military parade with marching troops and tanks to trample it - and as the dust settles, a kid on a pogo stick bounces on it. The man blithely says "I didn't feel a thing!"

Fan Fiction

 * In "Space Vixens!", an anime-esque Doctor Who elseworld, the protagonists' ship is almost sabotaged by two insurance agents -- until the vital control unit gets a lump of shrapnel through it. Fortunately (from their point of view), that only breaks the screen. Unfortunately, what's left promptly gets trodden on by two different people, and shatters into a dozen fragments.

Film
"Ed: Oh, Frank! It's horrible. It's so horrible!
 * At the end of The Naked Gun, Vincent Ludwig falls off a high ledge onto a street below where he gets hit by a bus, flattened by a steam-roller, and then trampled by a marching band playing "Louie Louie."

Frank: (Comforting Ed) I know...

Ed: My father went the same way..."

Western Animation

 * The Simpsons
 * The episode "Lisa's Sax" sees Lisa's prized saxophone sail out her bedroom window and into the street where it's run over by a car, a truck, stamped on by Nelson (who then points at it and mocks, "Ha ha"), and concludes with a man on a tricycle who falls over to the side when his front tire hits what remains of the flattened saxophone.
 * And to top it all off, the Sax produces a "Wah Wah" sound after all that.
 * Another episode sees Milhouse crushed by an actual parade, featuring an endless number of marching bands, parade floats, elephants, etc.
 * Sideshow Bob is run over by parade elephants in "Cape Feare" right after he said, "Surely there's no harm in laying the middle of a public street."
 * In the Rocko's Modern Life short "Eyes Capades," Rocko's new glasses end up getting run over by a truck, a motorcycle, a roller skater, and an old lady with a cane.
 * Also, when Filbert is fired by Rocko, he himself ends up in the street, where he is run over by a marching band, cars, a cruise liner, a bullet train, and a stray moon.
 * Kenny's first ever death on South Park sees him blasted onto a road by an alien raygun, trampled by a herd of stampeding cows, and the killing blow comes when he's run over by Officer Barbrady's police cruiser. After that, his body is eaten by rats.
 * A variation occurs in The Grim Adventures of Billy and Mandy, after Billy's bike crashes into a tree, it is hit by a meteor and swallowed up by the Earth.
 * Happened in one episode of Chowder with the object being Mung's childhood bicycle, I mean Dice Cycle.
 * Happens to Candace on an episode of Phineas and Ferb when she's given her new cellphone, told if she loses this phone she won't be getting a new one. Cue Candace tripping on a rug, her phone flies out of her hand, out the window, onto a branch, onto a sunflower and landing seemingly safely in a bunch of leaves. In comes the delivery man for Phineas and Ferb's project of the day, puts down a heavy box on the phone, drives over it, backs over it not two, not three... but EIGHT times.