When Australia, the Olympic favorites, beat New Zealand for gold in women's rugby sevens many wondered about the teary dance performed by the silver medalists following the match. Performing a version of this dance, called the Haka, has been a tradition of New Zealand national rugby teams since 1905.
Both the men's and women's national teams perform it during international play. It is a "Māori war dance traditionally used on the battlefield, as well as when groups came together in peace," according to New Zealand Tourism. The dance is used as a show of strength, which makes sense in rugby for very obvious reasons.