Zerophilia is a 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.
Since Sean has Zerophilia, he fears if he has sex with his girlfriend, he'll wake up in the morning as Shauna.
by ZerophiliacsHaveMoreFun January 2, 2010