Ever heard of Bay to Breakers ? Well, think of it as kind of race where running in costume isn’t only accepted, it might be the least surprising thing you see all morning. The San Francisco 12K has been around since 1912 , moving from the city’s bay side toward Ocean Beach and evolving over the decades into one of the country’s strangest, most beloved running traditions. This year’s race on May 17 included the classic 12K, a 15K option, teams, and the famous centipede division, where groups of 13 to 15 runners complete the course connected together. But if multi-legged bugs aren’t your thing, don’t worry—there’s also the salmon. For years, a group of costumed runners has turned Bay to Breakers into Breakers to Bay, dressing as giant salmon and running the course backward. Not “backward” as in facing the wrong way, thankfully. Backward as in starting near the breakers and heading toward the bay, “swimming upstream” and going against the race’s current, so to speak.…