"The Five
Forbidden Things," or "the five m's," is a phrase that literally
means "the five forbidden things": Tantra is a hidden, ritual-based
religious system that uses a collection of five objects for devotion.
Madya (wine), Matsya (fish), Mamsa (meat), Mudra (fermented
or parched grain), and Maithuna (fermented or parched grain) are the five names
that begin with the letter "m." (copulation).
They are utilized in "left hand" (vamachara)
tantra in their natural form, and in "right hand" (dakshi nachara)
tantra through substitution.
All five are frowned upon by "respectable" Hindu
culture (the final because it is considered adulterous), therefore their usage
in tantric ritual must be seen in context.
The ultimate oneness of everything that exists is one of the
most widespread tantric conceptions.
From a tantric viewpoint, affirming that the whole cosmos is
one principle—often understood as the activity of a certain deity—requires the
adept to abandon all dualistic ideas.
The "Five Banned Things" give a ceremonial manner
of breaking down dualism, since the adept breaks society norms prohibiting
intoxication, non-vegetarian eating, and illegal intercourse in a purposeful
endeavor to sanctify what is not mally forbidden.
Tantric adepts argue that such ceremonial usage of banned
objects demonstrates that their practice entails a higher level of exclusivity
(adhikara) and is therefore superior to general practice.
See Arthur Avalon's (Sir John Woodroffe's) Shakti and
Shakta, 1978; Swami Agehananda Bharati's The Tantric Tradition, 1977; and
Douglas Renfrew Brooks' The Secret of the Three Cities, 1990 for further
details.