Googled this from Wikipedia...
[edit] NFL trademark issues
The NFL is vigilant on stopping unauthorized commercial use of its trademarked terms "NFL," "Super Bowl," or "Super Sunday"; as a result, many events and promotions timed to the game but not sanctioned by the NFL are forced to refer to it as "the Big Game", or with other generic descriptions.[14]
In 2006, the NFL made an attempt to trademark "The Big Game" as well. However, it withdrew their application in 2007 due to growing commercial opposition to the move.[15]
How F'in stupid!!