http://en.wikipedia.org/wiki/Black_Mass
In
Christian tradition,
Black Mass is the name given to a ceremony supposedly celebrated during the
Sabbath, which was a parody of the Christian
Mass. Its main objective was the profanation of the
host, although there is no agreement among authors on how hosts were obtained or profaned; the most common idea is that they were profaned by means of some ritual related to sexual practices. Authors also disagree on which rites were performed during the ceremony.
Some scholars believed that the host was replaced by a
toad, a
turnip or a bit of dry flesh, but most judges and authors believed that true hosts were given by Christian
priests that had made a
diabolical pact to the attendants to the Sabbath to be profaned by them.
As it was believed that the culmination of this mass was an
orgy, the term was later applied to a sexual orgy.
The
Church of Satan occasionally stages Black Masses, not as an act of worship, but rather to quite deliberately shock the general public (especially Christians) and thereby draw media attention.
In
Mystical Satanism it is the ultimate ritual to obtain magical powers. The altar is an exposed woman, whose
vagina is the
tabernacle. A
host is added to the vagina, if possible a real host is obtained. While the host is added the ritual requires reciting distorted
psalms, cursing
Jesus and praising
Satan. The woman is then defiled by the practitioner hoping to obtain magical energies from the ritual.
This defintley does not sound like the LHP members I have met. Here are some other websites that may help out.
http://www.themystica.com/mystica/articles/b/black_mass_the.html
http://altreligion.about.com/library/graphics/bl_blackmass.htm