Heyoka is a spirit in Lakota Mythology that is seen as a trickster. It speaks, moves and reacts in an opposite fashion to the people around it. It is not a spirit that people wish to meet at any time; it usually appears to people when it wishes to take something from you or cause some sort of mayhem. The Lakota people have learned to respect it enough to leave it be, avoiding it as much as possible.
Heyókȟa are thought of as being backwards-forwards, upside-down, or contrary in nature. This spirit is often manifest by doing things backwards or unconventionally—riding a horse backwards, wearing clothes inside-out, or speaking in a backwards language. For example, if food were scarce, a Heyókȟa would sit around and complain about how full he was; during a baking hot heat wave a Heyókȟa would shiver with cold and put on gloves and cover himself with a thick blanket. Similarly, when it is 40 degrees below freezing he will wander around naked for hours complaining that it is too hot. A unique example is the famous Heyókȟa sacred clown called "the Straighten-Outer":
He was always running around with a hammer trying to flatten round and curvy things (soup bowls, eggs, wagon wheels, etc.), thus making them straight.— John Fire Lame Deer, Seeker of Visions, p250
During the Sun Dance, a Heyókȟa sacred clown may appear to tempt the dancers with water and food and to dance backwards around the circle in a show of respect. If a dancer looks into the mirrored eyes of the Heyókȟa, his or her dance is finished.
In Lakota mythology, Heyókȟa is also a spirit of thunder and lightning. He is said to use the wind as sticks to beat the drum of thunder. His emotions are portrayed opposite the norm; he laughs when he is sad and cries when he is happy, cold makes him sweat and heat makes him shiver. In art, he is depicted as having two horns, which marks him as a hunting god.
Social role 
The Heyókȟa symbolize and portray many aspects of the sacred, the Wakȟáŋ. Their satire presents important questions by fooling around. They ask difficult questions, and say things others are too afraid to say. By reading between the lines, the audience is able to think about things not usually thought about, or to look at things in a different way.
Principally, the Heyókȟa functions both as a mirror and a teacher, using extreme behaviors to mirror others, thereby forcing them to examine their own doubts, fears, hatreds, and weaknesses. Heyókȟas also have the power to heal emotional pain; such power comes from the experience of shame—they sing of shameful events in their lives, beg for food, and live as clowns. They provoke laughter in distressing situations of despair and provoke fear and chaos when people feel complacent and overly secure, to keep them from taking themselves too seriously or believing they are more powerful than they are.
In addition, sacred clowns serve an important role in shaping tribal codes. Heyókȟa's don’t seem to care about taboos, rules, regulations, social norms, or boundaries. Paradoxically, however, it is by violating these norms and taboos that they help to define the accepted boundaries, rules, and societal guidelines for ethical and moral behavior. This is because they are the only ones who can ask "Why?" about sensitive topics and employ satire to question the specialists and carriers of sacred knowledge or those in positions of power and authority. In doing so, they demonstrate concretely the theories of balance and imbalance. Their role is to penetrate deception, turn over rocks, and create a deeper awareness.
For people who are as poor as us, who have lost everything, who had to endure so much death and sadness, laughter is a precious gift. When we were dying like flies from white man's disease, when we were driven into reservations, when the government rations did not arrive and we were starving, watching the pranks and capers of Heyókȟa were a blessing.—John Fire Lame Deer, Seeker of Visions, p250
Thunder dreamer 
It is believed among the Lakota that if you had a dream or vision of birds you were destined to be a medicine man, but if you had a vision of the Wakíŋyaŋ Thunderbird, it was your destiny to become a Heyókȟa, or sacred clown. Like the Thunderbird, the heyoka are both feared and held in reverence.
When a vision comes from the thunder beings of the West, it comes with terror like a thunder storm; but when the storm of vision has passed, the world is greener and happier; for wherever the truth of vision comes upon the world, it is like a rain. The world, you see, is happier after the terror of the storm... you have noticed that truth comes into this world with two faces. One is sad with suffering, and the other laughs; but it is the same face, laughing or weeping... as lightning illuminates the dark, for it is the power of lightning that heyokas have.—Black Elk, quoted in Neihardt (1959), p160
The Heyoka are healers and have many functions, for example healing through laughter and awakening people to deeper meaning and concealed truth and to prepare the people for oncoming disaster with laughter.
See also 
- Clown society
- Crazy wisdom
- Contrary (social role)
- Tales of the Beanworld - which has a character named "Heyoka"
- The Fool (tarot card)
- Borges, Jorge Luis. (1969). The Book Of Imaginary Beings
- Lame Deer, John (Fire) and Richard Erdoes. Lame Deer, Seeker of Visions. Simon and Schuster, New York, New York, 1972. Paperback ISBN 0-671-55392-5
- Heyoka magazine, Pete Catches Interview
- Wilson D. Wallis. Heyoka: Rites of Reversal. Lakota Books, 1996 reprint.
- Thunderbird and Trickster by Steve Mizrach