A 23-year-old woman has paid £210 for the privilege of slapping a stranger around the face with a wet fish.
Mr Fillmore hopes to raise awareness of strokes
Student Lucy Berry won the chance to slap Ben Fillmore, 24, who had begun an auction on the eBay website to raise money for the Stroke Association UK.
Ms Berry, who used two rainbow trout, said after the slap at Hyde Park's Speakers Corner in London: "It was extremely satisfying."
Mr Fillmore hopes to raise £10,000 for the charity.
Ms Berry, who was allowed to choose the type of fish used in the slapping, said: "It is kind of a dream of mine.
"I read a book about someone slapping someone with a fish when I was a child and thought it would be a great way to vent anger."
Luckily for Mr Fillmore - who came up with the idea after watching a Monty Python sketch - Ms Berry was not looking for a way to let off steam on Saturday.
"It felt ok," he said. "My face feels a bit taut and the fish really stinks. It felt very slimy but was definitely worth it."
His next challenge is to conquer Mount Everest.
"It's great to raise money but I also want to raise awareness," said Mr Fillmore.
The Stroke Association works to reduce strokes through research and health education and support people and their families affected by the condition.