Paul Pierce is nicknamed "The Truth" based on a comment that Shaquille O'Neal made to a reporter after an NBA game in 2001. Pierce put up 42 points while playing for the Boston Celtics against O'Neal's Los Angeles Lakers. Despite Pierce's efforts, the Celtics went down 112-107 that night.
On March 13, 2001, a young and inexperienced Paul Pierce shot 13 for 19 from the field and impressed most onlookers. After the game, while in the locker room, Shaquille O'Neal approached Steve Bulpett of the Boston Herald and told him to write "Paul Pierce is the truth." Although there was a lot of hype surrounding Pierce, O'Neal was awestruck at his skill level. Throughout Pierce's long and successful NBA career, the nickname has stuck.