Gringo Bay seniors are loco if they think that Cinco de Mayo is Mexican Independence Day, celebrating the battle of Puebla in 1862 where the French were defeated. You’re way off base, amigos. Mexican Independence Day is September 16. Cinco de Mayo, if fact, is barely celebrated south of the border. It’s here in the US that the partying gets serious. You’ll find roaring fiestas all over the Bay Area –in Oakland, San Jose, Sausalito and, of course in Dolores Park where this year organizers have added a mass zumba-athon (which is actually Brazilian). There’s a more upscale ($55 per) celebration at SF’s Ferry Building. And if you head out to the game between Milwaukee and Los Gigantes de San Francisco at ATT Park youll get a bobblehead of pitcher Sergio Romo.