Rule 63

Enforced by all the basement-dwellers who were either uncomfortable with their true sexuality or of an unsatisfiable nature that decided to go gender-bender on drawing their favorite cartoon characters, Rule 63 states that "for any given male character, there is a female version, and vice versa".

	“	There is always a female version of a male character (and vice versa).	„
	—Rule 63, A less known though still delicious rule.

Unlike a lot of Rule 34, generally being only a penis cumming into a tongue shopped into an image, creating Rule 63 requires a little more talent, as not only must the artist imagine a character as its gender counterpart but fully construct it as well. But keep in mind that all of the people who draw Rule 63 are not only homosexuals to some extent but alone-dying virgins as well, so don't be surprised if you see a Rule 63 that's also Rule 34.

Mistakes

While some may come to think that cross-dressing or futanari are Rule 63, this is a false assumption as the same gender still persists. To become Rule 63, a character must go through full sex-change.

If it has both genders, it is not Rule 63
What to do when one's gender is not specified?
That is still a man so, no
Dickgirls are futa, not 63
Someone fails at numbers

Other mistakes involves angry rabid delusional LGBTQ+ Tumblrinas or Twatters violently forcing the character to be canonically fat ugly empowering disabled diverse trans whenever they see Rule 63.