Haka is the name for a group of ceremonial dances of the Maori of New Zealand and surroundings. The traditional cries and movements are danced to invoke Gods and ancestors.
Haka war dance is done as to impress the opponents. Besides this war dance (Peru) there are haka (both singular and plural) for funerals, celebrations, or welcoming guests or tourists, often for traditional hangi, the welcome meal. There are also haka for women, children or mixed groups.
Some dances and verses are fixed, others leave room for improvisation from the dancers. The text of the haka is not sung, but chanted to the gods.
Worldwide, probably the most famous haka is the Ka Mate, which for years is performed by the All Blacks, the New Zealand rugby team, before the start of each game.
The dance itself consists of a series of gestures, and starts from a bended knees straddle. The dancers show off muscles and strength, they hit on the chest, arms and thighs, and are stomping on the floor. Also, the face plays along. They show the whites of their eyes, and stab a long tongue. A haka is meant to impress and frighten audiences and opponents. Laughing there is seen as an insult. Frightened people are not supposed to laugh.