A few weeks back I attended the Boryeong Mud Festival, a.k.a Mudfest, which is held in an otherwise sleepy beach-town and basically involves coating your body in mud and frolicking on the beach, while drinking. Yes, it's as fun as it sounds.
According to the Korean Tourism website, Mudfest is the most popular international festival in Korea. "During the festival period, tourists flock to the area to experience the beneficial properties of the Boryeong mud, and alto to have lots of fun. Fully immersed in both the mud and the festival's great atmosphere, visitors enjoy mud wrestling, mud sliding and even swimming in the mud mega tub. Visitors feeling particularly energetic can try the marine mud-training course, whilst those looking for something more chilled can relax in the mud massage zone. In the evening, music and fireworks continue the party on the beach" (Official Site of Korean Tourism).
Some pictures of my friends and I at Mudfest: