Any person with Zerophilia, the rare genetic condition affecting those who possess an extra "Z" chromosome in addition to the standard gender-determining X and Y
chromosomes. Following their first experience of
sexual intercourse, Zerophiliacs may change gender whenever they are sexually aroused. The
International Organization of Zerophiliacs provides testing services and resources for those with Zerophilia.
When she noticed her boyfriend, Jake's, penis occasionally
disappeared, Mary submitted his hair for testing to The
International Organization of Zerophiliacs and confirmed her hopes: Jake is a Zerophiliac.