Looking for an excuse to parade naked through the streets? Well here it is: Coney Island’s mermaid parade, held the first Saturday after summer solstice every year since 1983. New Yorkers in large numbers don creatively skimpy mermaid and mermen costumes (some don’t dress at all) and march along Brooklyn’s Surf Avenue to celebrate summer. What began as a neighborhood fundraiser, reports Buster Phillips at www.ironminds.com, is now a charmingly goofy spectacle full of exhibitionist brass bands and bizarre floats. If you’re thinking this might be fun in your staid hometown, remember there is safety in numbers; even in Rudy Giuliani’s straight-laced New York, there are no arrests. (But bring lots of SPF45 sunblock.)