In the sense of how clowns serve their culture:
Members of a clown society always dress in some kind of a special costume reserved for clowns, which is usually an absurdly extreme form of normal dress.
In the case of the Zuni clown society of the Pueblo Indians, "one is initiated into the Ne'wekwe order by a ritual of filth-eating" similar to Eucharist; "mud and excrement are smeared on the body for the clown performance, and parts of the performance may consist of sporting with excreta, smearing and daubing it, or drinking urine and pouring it onto one another". The sacred clown and his apparently antisocial behavior is condoned in Indian ceremonies.
While in their costume, clowns have special permission from their society to parody or criticize defective aspects of their own culture. They are always required to be funny. Other persons living within the same culture may recognize a clown when they see one, but seldom consciously understand what the clowns do for their society. The typical explanation is "He's just a funny man."
In the case of the "jester" at the English Royal Court with his cap of bells and pigs bladder stick he was allowed to make fun of, be indelicate and sometimes downright rude to members of the royal family and their entourage without fear of reprisal
Clown societies usually train new members to become clowns. The training normally takes place by an apprentice system, although there may be some rote schooling as well. Sometimes the training is improvisational comedy, but usually a clown society trains members in well known forms of costume, pantomime, song, dance, and common visual gags. Occasionally these include a scripted performance, or skit, which is part of a standard repertoire that "never gets old," and is expected by members of the culture that the clown society is part of.
In Native North America. humor assumes "a sacred position within ceremonials; examples are found in Trickster traditions, Pueblo clown societies, Cherokee "Booger" dances, and aspects of the Northwest Coast Potlatch. Humor is a fundamental aspect of Native American life, and has many purposes related to sacred rituals and social cohesion.
As a general rule, a comedian says funny things, a comic does funny things, and a clown does things funny. Also, a comedian has to take personal responsibility for his/her humour and its consequences, whereas a clown's costume provides social license.