Shin kicking is the most brutal green sport we researched. It is exactly what it sounds like — two guys (and it's almost always guys; 2009 was the first year a woman competed) stand toe to toe, grab each other's lapels, and start kicking at each other's shins. It's simple, requires no equipment, and can be practiced just about anywhere. Shin kicking is part of the Cotswold Olimpick Games, a celebration of traditional games and sport held in Cotswold, England, since the early 1600s. The modern-day version of the games was started in 1963 and besides shin kicking, features other green sports like championship of the hill, tug of war, and a 5-mile cross-country race.