Rule 34

Rule 34 is a commonly accepted Internet rule that states "If it exists, there is porn of it. No exceptions." The idea is that pornography or sexual material exists for any conceivable subject. Though it has been suggested there are limitations on the rule, others suggest there may not be any.

It is most commonly used on imageboards and forums as fan art or fanfic media, for a variety of reasons.

Rule 34 and furry
As with mainstream multimedia, sites and examples, the same rule applies to any media created in the furry fandom.

This rule often runs in correlation with:
 * Rule 36: If it exists, someone has a fetish for it. No exceptions.
 * Rule 63: There is always a female version of a male character (or vice versa). No exceptions.
 * Rule 76: There is always a shemale version of a female character. No exceptions.
 * Rule 85: If it exists, there is a pony version of it.