As the rodeo crowd cheers in anticipation of the next six-second ride, Joey Nowacek makes sure his grip is secure. He taps his helmet and signals he is ready to go as he squeezes his cowboy boots against the side of the anxious animal. Then the chute bursts open and the beast darts out, bouncing the cowboy on its back. The event . . . isn't bull riding — it's mutton bustin' . . . and the cowboy is only 5 years old. Some people call this popular rodeo event "baby bull riding" because of its similarities to the sport...