Pluto (Disney) was originally created as Dippy Dawg" and "was created as a human character, as opposed to Pluto who was a pet, so [Goofy] walked upright and had a speaking voice". This problem was humorously illustrated in the film "Stand By Me" in which one of the boys ponders, "Mickey's a mouse, Donald's a duck, and Pluto's a dog. What's Goofy?" Also in the series "Funniest Pets & People" a dog "mentions" why couldn't he have pants because Goofy was a dog and had pants. There is also an episode of the Disney Channel series "Even Stevens" called "Scrub Day" wherein
Cartoon physics a cliff, gravity has no effect until the character notices. In words attributed to Art Babbitt, an animator with the Walt Disney Studios: "Animation follows the laws of physics—unless it is funnier otherwise." Specific reference to "cartoon physics" extends back at least to June 1980, when an article "O'Donnell's Laws of Cartoon Motion" appeared in "Esquire". A version printed in V.18 No. 7 p. 12, 1994 by the Institute of Electrical and Electronics Engineers in its journal helped spread the word among the technical crowd, which has expanded and refined the idea. These laws are outlined on dozens of websites.