Earl "Yogi" Strom was an American professional basketball referee for 29 years in the National Basketball Association (NBA) and for three years in the American Basketball Association (ABA). Strom is credited as one of the greatest referees in the history of the NBA and was known for his flamboyant style and ability to control the game. Nicknamed "The Pied Piper", the assertive Strom made foul calls with his whistle by using a "tweet-pause-tweet-tweet" tune and pointing at the offending player. In addition to calling fouls with flair, he was known for ejecting players from games with style and he sometimes supported his rulings with physical force.

The National Basketball Association (NBA) is a professional basketball league in North America composed of 30 teams. It is one of the major professional sports leagues in the United States and Canada and is considered the premier professional basketball league in the world.