Wikipedia
Shin-kicking, also known as hacking or purring, is a combat sport that involves two contestants attempting to kick each other on the shin in order to force their opponent to the ground. It has been described as an English martial art. It originated in England in the early 17th century, and was one of the most popular events at the Cotswold Olimpick Games until the Games ended in the 1850s. It also became a popular pastime among Cornish miners. In the 19th century the sport was also practised by British immigrants to the United States. It was included in the 1951 revival of the Cotswold Olimpick Games, and remains one of its most popular events, run as the World Shin-kicking Championships. The event now draws crowds of thousands of spectators.
During each round, the combatants face each other and hold on to each other's collar. Traditionally (in the Cotswold Olimpicks) they wear white coats, representing shepherds' smocks. They typically attempt to strike their opponent's shin with the inside of the foot as well as their toes. Success in the event requires both agility and the ability to endure pain, the loser crying out "sufficient" when he has had enough. The matches are observed by a referee, or stickler, who determines the score of the match. Modern competitions are won by the combatant who wins two out of three against his competitor.
Legend has it that some shin-kickers wore steel-toe boots during the competitions and tried to build pain tolerance by hitting their shins with hammers. In modern competitions the combatants are required to wear soft shoes and stuff their trouser legs with straw for padding. Ambulance crews also attend the events in case of injury.