Stripped down to his sunglasses and hiking boots, McCray Winpsett, 37, said he understands the disgust of residents who would prefer not to see the body modifications and sex enhancement devices sported by some of the Castro nudists. But he thinks Mr. Wiener’s prohibition goes too far in undermining a tradition “that keeps San Francisco weird.”

“A few lewd exhibitionists are really ruining it for the rest of us,” he said. “It’s my time to come out now to present myself in a light and show what true nudity is all about so people can separate the difference between what a nudist is and an exhibitionist is.”

Because clothes are required to enter City Hall itself, demonstrators who try to disrobe at the Board of Supervisors meeting will be escorted out by sheriff’s deputies.