My worlds 
In this reality, there are two interconnected worlds, two universes.
The mundane world
The mundane world is inhabited by mundanes, plain normal boring folks, all of them are human, no anthro animals in the mix.
More often than not, the cartoon world bleeds into the mundane world in the form of anomalies. The funrooms, the slide that never ends, toilets that turn alive and pink cursed underwears are examples of that.
The "zootopia" world
Explored in the funrooms story, is an intermediate world between the mundane world and the cartoon world. The laws of physics there are the same as on earth.
The cartoon world
The cartoon world is inhabited by toons.
Toons look very different, they have fewer details and are much more obnoxiously colored. Their body is made of a substance that's both malleable like clay and sleek like rubber. Rarely they wear a full coat of fur that's very soft and fluffy.
Toons have a complete lack of organs, instead food is stored in their mass and converted into the same substance. This process is not well-understood and nobody knows why toons are alive since mundanes need blood, lungs, a brain and a heart to live.
Also, in the world of cartoons, except for physical laws of nature, everything is a social construct.
As a result, placebo is very potent. If a character believes eating certain food makes them strong, it WILL happen.
For more information, check out Toon Physics or Toon Biology!