SAN FRANCISCO (CBS SF) — One of the people featured in David Letterman’s visit to San Francisco in 1996 took it all off on national television — literally.

“One the one hand, I was startled, nervous, not knowing what came next,” said audience member John, a professor at Stanford University who now works at Intel. “On the other hand, it was sort of by design to get some attention of some sort.”

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Letterman offered John to take a shower — for charity — in his dressing him featuring a 49ers shower curtain.

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“We aging, jaded hippies just go with the flow, obviously,” said John, who used a math theorem to get a spot in line that would land him an aisle seat. “It was fun. I had no idea it would come back to haunt me 20 years later.”

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There are only five David Letterman shows left. Thursday’s episode will feature George Clooney and Tom Waits.