Extreme Mud Games, Norman

You're going to have to get your hands dirty if you want to tackle the physical challenges that dot the 5K Extreme Mud Games racecourse. And your legs, chest, arms, and ear lobes. Each obstacle, from the cargo climb to the wire crawl is designed to test participants' grit, tenacity, and fearlessness in the face of filth as they run in pursuit of glory and a medal that greets all racers at the finish line. The event, while extreme, is family-friendly and open to runners ages 14 and up, and there's even an abbreviated course—about 1.5 miles—where kids ages 4-13 can showcase their stamina and mud pie making abilities.