The Boston Celtics have won 17 NBA championships and retired 22 jersey numbers in their 74-year history. Avert your eyes, Los Angeles Lakers fans... In the latest episode of Nissan's "The Pick Up," Grousbeck confirmed to host Brian Scalabrine the number 39 is a reference to Game 6 of the 2008 NBA Finals, when the Celtics won the title by beating the Los Angeles Lakers by -- you guessed it -- 39 points.