Most races give finishers souvenir T-shirts; this one offers tattoos. The message is clear: This is not your typical weekend race. Participants navigate a 10-mile obstacle course patterned after one developed by British Special Forces as a training program. Competition is done in teams with members helping each other scale 12-foot walls, navigate tunnels and slog through mud. By the way, if you don't want the tattoo, the T-shirt option is available.