Brown posted a message to his Maryland counterpart, Gov. Martin O’Malley, late Friday on Twitter, offering a book on California history if the San Francisco 49ers lose to the Baltimore Ravens.

The Democratic governor posted a photo of a weathered copy of the 1949 book “California: The Great Exception,” by Carey McWilliams. He said it details the state’s exceptionalism on and off the field.

O’Malley responded on Twitter with a more traditional sports offering, saying “I see your book, and I raise you a case of Natty Boh,” or National Bohemian beer, which hails from Baltimore.

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