Borborites

According to Epiphanius Panarion/Adversus Haereses chapter xxv, xxvi and Theodorets Haereticarum Fabularum Compendium the borborites (or barbelos, barbelites, phibionites, stratiotici, coddians etc) were a extraordinarily filthy and evil Gnostic sect. The word "borborite" comes from the greek word borboros which means "mud[?]".

Epiphanius says the borborites were inspired by Sethianism, and had as a distinct feature of their rituals elements of sexual sacramentalism, including homosexual intercourse, smearing of hands with menstrual blood and semen, and consumption of the same as a variant of eucharist. They were also said to extract fetuses from pregnant women and consume them.

As all these tellings about the borborites come from their opponents, we don't know for sure if they are true or exaggerated. This concerns especially Epiphanius.