Toon Transformation

"I... I'm a cartoon!

—Richard, The Pagemaster

When somebody might end up in another world, artists and crew members might cut the budget, just by making them into a cartoon or the such. Whether it's through being taunted, going through a magic portal, or whatever else, but on the other side, those live action folks end up as cartoons.

Media that has this trope usually ends up as mostly a cartoon.

Not to be confused with Medium Blending or Art Shift.

Examples of Toon Transformation include:

Advertising

There were a handful of "Crunchatize me, Cap'n!" commercials for Cap'n Crunch cereal in which the kids would get surrounded by a hail of cereal and emerge as cartoons.
Some Esurance insurance commercials had Erin Esurance turn live action people into cartoon characters.

Anime

In the strictest sense not really an anime example perse but this was what a company called Toon Makers had planned for Sailor Moon if they had gotten the rights instead of DiC's eventual Cut and Paste Translation. They were going to have the civilian scenes filmed in live action and then the girls would turn animated in a very Filmation's She Ra Princess of Power-esque style when they transformed. Also they were going to go literally sailing... in space. See here the only available clip of (which was recorded from a convention screening on a camcorder hence the low quality & background noise) of what is commonly nicknamed "Saban Moon" due to people assuming the company who made it was Saban (they DID commission it).
Training with Hinako starts with showing a live-action version of Hinako, but she's very quickly Trapped in TV Land as an anime character for the remainder of the series.

Comic Books

The Archie Comics Sonic special, Sonic Live. Sonic pulls two live-action kids into their television screen, turning them into cartoons.
The Marvel Comics character The Awesome Slapstick. Junior high school class clown Steve Harmon's molecules stretch across 3741 dimensions, turning Steve into a cartoon clown.

Film

In the 1996 movie adaption of James and the Giant Peach, James, and an assortment of insect and arachnid friends, become claymation figures when they go inside the peach. Justified, since it is a magic peach, enchanted by crocodile tongues.
- Subverted at the end of the film where even though James changes back after climbing out of the peach, the insects all remain claymation.
The Fat Albert has an inversion. Fat Albert and the gang start out as cartoons, then become live-action when they jump through the TV screen.
On the movie of The Adventures Of Rocky And Bullwinkle, Boris, Natasha and Fearless Leader become live actors as they go through a television screen.
- When Rocky and Bullwinkle do the same, they simply turn into Cel Shaded versions of themselves, a discrepancy that is Lampshaded later on.
The Pagemaster - A prominent example. A wave of paint covers the library, turning the main character and the library into a cartoon.
Enchanted, where it's also the invert: A cartoon princess becomes a live actor in real life.
Cool World is an in-verse sitch, apparently. Any "human" who is killed by a "doodle" resurrects as a doodle themselves. The artist is also afflicted when the dimensional barrier is broken.
- Holli's goal is to become "real" by having sex with a human. It works, but the effects are unstable, and she starts going back and forth between cartoon and live action.
Stay Tuned, where Roy gets Trapped in TV Land and after one channel switch, and becomes a cartoon mouse menaced by a giant cat.
The end credits of the TV movie Phineas and Ferb The Movie: Across the 2nd Dimension, in which the rock star Slash plugs into a tricked-out amp, with a spark of electricity that travels down the wire to his bass, which spreads to his body turning him from live action to animated.
In Rock-a-Doodle - The owl sings musical notes, turning the little boy into an animated cat (as well as his room.)
The 1970 movie The Phantom Tollbooth, in which Milo enters a tollbooth, which makes him animated (he messes with this quite a bit, realizing what the tollbooth does), to get to the Kingdom of Wisdom.
A Deleted Scene in Who Framed Roger Rabbit? originally had Eddie Valiant gain an animated pig's head over his own head when he entered Toontown.
Happens to Milo the Jack Russell terrier at the end of The Mask after donning the Mask of Loki to fight off Dorian Tyrell's mooks.
The fish in the film adaptation of The Cat in the Hat starring Mike Myers.
The Autobots and Decepticons in the live-action Transformers films have CGI robot modes, but live-action vehicle modes.
Zig-zag: Yellow Submarine caps off with the live action Beatles telling what they took with them from the movie as souvenirs (Paul's "love" appears in his hand animated), with John telling the others that singing will stave off an impending Blue Meanie attack.

Live-Action TV

This happened on Fringe', and even allowed Leonard Nimoy to make a guest appearance after his last live action TV appearance.
If there had been another season of Quantum Leap, there were plans that Sam would leap into an animated character.
The second Eureka Christmas Episode "Do You See What I See", in which a wave of color turns the city into multiple styles of animation and cartoony effects, which also makes Jack's jeep come alive, Andy becoming a cartoonish robot, and Jo becoming a Disney-like princess.
- All of this was the result of an interactive storybook unexpectedly interfering with a large-scale holoprojector.
The 2006 Cartoon Network television movie Re-Animated, where Golly temporarily turns Jimmy into a cartoon knight on a horse, to save Robin from being run over by a train.
There was a lot of this going on in the (partially animated) Farscape episode "Revenging Angel," which transitioned between "live action in the real world of the show" scenes, and the "live action cartoon scenes" and "animated cartoon sequences" inside John Crichton's head.
In Life On Mars as a result of accidentally ingesting a drug which one depends on whether Sam's really in a coma or really back in time, Sam has a hallucination in which he, Gene Hunt and a random sexual predator are all rendered in the same stop motion animation as in Camberwick Green.
In the Angel episode "Smile Time" Angel finds himself turned into a muppet like felt puppet, not strictly speaking a cartoon but related.

Music Videos

The hero of the music video for A-ha's "Take On Me" switches between being a drawing and live-action several times.

Puppet Shows

The Nineties intro to Plaza Sésamo, where some of the puppets and kids get on a bus, and go through a strange rainbow, taking them to an animated Plaza Sésamo.

Stage Shows

The late 90's/early 00's show at Disney MGM Studios, Disney's Doug Live!. It's the invert this time: Doug's animated friends jump out of the projected screen, and become live actors.

Web Original

Hewy's Animated Movie Reviews has a studio in the second dimension, where Hewy can host guest co-reviewers who are 2-D themselves. It gets destroyed when he tries to duplicate Flint Lockwood's food machine from Cloudy with a Chance of Meatballs.

Western Animation

The Doodlebops Rockin Road Show, where the animated Doodlebops play their instruments to create a tornado, that turns the selected kid who needs help into an animated character.
The direct-to-video series The Wacky Adventures Of Ronald Mc Donald, where Ronald gets onto a type of slide, and turns into an animated caricature of himself.
Kidd Video - the band goes through a mirror after being taunted by Master Blaster (the Big Bad), and goes to the Flipside (an animated world) through a mirror.
The Simpsons: In the second segment of a Halloween episode Bart and Lisa were sucked into a Itchy and Scratchy cartoon.
Captain N: The Game Master, in which Kevin, and his dog Duke are sucked into the Ultimate Warp Zone, and become cartoons in Videoland (it also appears that he got older in the process).
Bobby's World, where Howie occasionally turns into a cartoon for the show, during the Cold Open.
Inverted several times in the opening theme for Jackie Chan Adventures.
This happens to Lucky Piquel in Bonkers, which is a curious case as he was already animated but he changes from a realistic looking Disney human into a miniscule comedic looking toon. Much to his dismay given his attitude to toon shenanigans being less than a glowing one.