"Most people smile when they jump over flames, because, well, it's just fun," says Joe Reynolds, founder of Red Frog Events, a Chicago company that puts on extreme races and other events. The flame jump is one of a dozen extreme obstacles at Red Frog's signature event, the Warrior Dash, pictured here at the Pocono Raceway in Long Pond, Pennsylvania. The 5K run, which takes place in dozens of cities in North America and Australia each year, also requires participants to crawl through mud and under barbed wire. Founded in 2007, Red Frog posted $31.7 million in sales last year and is on track to host 85 events this year, including urban scavenger hunts and pub crawls.