Actions against ambush advertising are most common in sport (where major events such as the FIFA World Cup, Olympic Games, and the Super Bowl are prominent targets), as the practice can devalue and dilute exclusive sponsorship rights, and in some cases, infringe upon the organizers' intellectual property rights. Such actions may include restricting advertising in "clean zones" around an event site, removing or obscuring references to non-sponsors at venues, and requiring host countries to pass laws to grant the organizer legal rights to enforce clean zones, and to restrict the use of specific words and concepts to create unofficial associations with the event.