I have even heard some so-called tantric practitioners lie to have sex, claiming “if you do the union of male-female practice with me, you will achieve enlightenment.” Please note that if you run into this situation in the future, you must know the person who makes such a claim and the claim itself are both questionable. This is certainly not tantric practice; it is conducting an evil action in the name of Vajrayana. Vajrayana also points out if unwholesome deeds are committed in its name, they are considered more serious than the five hellish deeds. It is very important that we understand this clearly and correctly, and never blindly trust such people and such words.

- Quote from Gateway to the Vajrayana Path, "The Parable of a Black Snake"