BOSTON (AP) — ‘Tis the season to run nearly naked through the chilly streets of Boston. The Santa Speedo Run turns 20 on Saturday, when hundreds of people clad only in bikini-style swimsuits and Santa hats will dash through the city’s Back Bay neighborhood.

Organizers say the bawdy event has raised nearly $2 million for a local children’s charity.

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A group of bartenders and businessmen hatched the concept in 2000. Since then, participants have gathered to run — minimally clad — down posh Newbury Street while everyone else is holiday shopping.

Over the past two decades, the event has become so popular, the field has had to be capped at 700 so local authorities can handle crowd management. It’s also inspired similar runs as far as away as Minnesota and Budapest, Hungary.

Runners at the 20th annual Santa Speedo Run in Back Bay. (WBZ-TV)

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Insurance broker Ian Franke, who strips down every year for the run, told The Boston Globe: “You finish the day with wind chap in places you never expected to get wind chap. It’s a real issue.”

Proceeds benefit Play Ball, a nonprofit that funds team sports for underserved middle schoolers.

“I always say, it’s the longest mile of your life and the Speedo never gets any bigger,” said Mike Harney, an investment banker who founded Play Ball in 2006.

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