Nowadays they get their gear off and join in.
Sunderland JP Jacqueline Donkin was one of the 1,700 valiant, and chilly, souls who volunteered to take part in a show of mass nudity for artist Spencer Tunick.
Yesterday she got to see herself immortalised in his giant images as they were unveiled at the Baltic in Gateshead.
"It's absolutely marvellous. I'm very proud," she said.
It was, however, difficult to make her out in the seething mass of humanity artistically arranged at various locations along the Newcastle and Gateshead quaysides.
"That's me, up there," she said, pointing at the biggest picture in the exhibition. "A breast and a tattoo."
The experience of taking part in the art work, and seeing herself in the images, has particular significance for Jacqueline, 44, from Concord, Washington, since she volunteered after undergoing major surgery.
"I had recently recovered from having two lumps removed from my breast. I had just had the all-clear. I was very happy and it was chance to take part in something historic."
She says she enjoyed the experience – particularly when the sun came out and it warmed up a bit, and she didn't feel at all self-conscious.
She plans to put a print of one of the images on her desk. She works as a civil servant at Wear View House, Sunderland.
Recently appointed a JP, she begins her magistrate training in a fortnight's time.
Rather more visible in Spencer Tunick's images is Sunderland postman Colin Harrison, from High Barnes.
Not only is he pictured in the foreground of the largest photograph, but he's the only one out of the 1,700 who can be seen holding cigarettes.
He said: "We'd been out there ages, and I got a chance to go back to my clothes, so I got a couple of cigarettes for when we were standing around."
Colin, 46, was stunned to find himself featured so prominently.
"I'm shocked – I would rather have been somewhere at the back!"
He volunteered for the project after picking up a flyer about it at the Baltic.
He says his colleagues at Sunderland central post office have been very understanding.
"They think it's just a bit of fun," he said.
However, the taxi driver who took Jacqueline to the Sage was rather more taken aback.
"We had to be there at about 3.30 in the morning, and I told him I was going to get naked with a lot of other people in a Gateshead car park," she said.
lSpencer Tunick's exhibition is on Level 2 of the Baltic until Sunday, March 26.