Ultimate (Frisbee) is a sport played by seven people aside with a flying disc, or frisbee. It is a no contact and self regulated sport, which means there are no referees. Thus Spirit of the Game (thats Ultimate for sportsmanship) is super important. It also probably explains why people who play Ultimate are so incredibly cool and nice!
Read more on the sport and it’s rules here: http://www.wfdf.org/