The Superbowl is such a huge event in the United States that the country comes to a standstill when it is on.
Behind the Legend
It depends on how you define "standstill." During the game you can walk down any American residential street and not miss a moment of the action because the sound of the game can be heard from every house you pass. And many movie theaters shut off their films and pipe the Superbowl over their audio system to stop people from staying away from theaters in droves. But would this be considered a "standstill"?
One indisputably true fact is that the Superbowl has added a great deal to American culture. In fact, a few throwaway lines spoken during games have become permanent parts of the language, such as the San Francisco 49rs' coach's admonition that his players "check and double check" their strategy, Fran Tarkington's exclamation of "holy mackerel," and Howard Cosell's legendary, "I's regusted."