Speaking of the Road Runner and Wile E. Coyote, animator Chuck Jones and his team were said to follow these simple rules when creating the cartoons:
1. The Road Runner cannot harm the Coyote except by going “meep, meep.”
2. No outside force can harm the Coyote — only his own ineptitude or the failure of Acme products. Trains and trucks were the exception from time to time.
3. The Coyote could stop anytime — if he were not a fanatic.
4. No dialogue ever, except “meep, meep” and yowling in pain.
5. The Road Runner must stay on the road — for no other reason than that he’s a roadrunner.
6. All action must be confined to the natural environment of the two characters — the southwest American desert.
7. All tools, weapons, or mechanical conveniences must be obtained from the Acme Corporation.
8. Whenever possible, make gravity the Coyote’s greatest enemy.
9. The Coyote is always more humiliated than harmed by his failures.
10. The audience’s sympathy must remain with the Coyote.
11. The Coyote is not allowed to catch or eat the Road Runner.
The rules are made only slightly less interesting by their fiction; according to Wikipedia, long-time Jones collaborator Michael Maltese said he’d never heard of the rules.