The whole wrapping a strap around his balls and shocking them is the most ignorant thing i've ever heard. Whoever wrote that has obviously never seen a bull before or has a lick of common sense. First of all the flank strap is in front of his back legs. His balls are about a foot and a half farther back. Unless you can find a bull with nuts the size of a truck tire it is impossible to get this strap around his balls. think about it. if his balls were that far up on his stomach it would be a hell of a lot harder for him to mate. Like most four legged animals his nuts are way back right under his butthole. Are your nuts on your belly? No they're right back there by your butthole just like any other animal.
Secondly the bull owners would never allow someone to come close to damaging the bull that way. One shot of spunk from one of these bulls is sometimes worth several thousand dollars. You're not going to let some cowboy wrap his balls up with rawhide just to get a good ride.
Third if a bull was in that much pain it would be bucking in the chute. Sometimes they kick up a little but they're not jumping all over hell. They know ramming into those walls is more painful than that strap or the cowboy sitting on them. Once the gate opens they're all over the place because now the strap, the cowboy, and the shock of being thrown into a wide open arena with blinding lights has become the greater annoyance.
fourth, watch a bull ride. When is a bull the most riled up? the gate opens, he goes nuts. Cowboy comes off, he may still buck a little, after all you don't run a sprint and then just lay down. he's still going to kick a little but then he calms down real quick. He'll ram at the cowboy and the bull fighters cause he don't want them climbing up on him when he just got rid of the last jerk that was on his back. The flank strap is still on but hes not writhing in pain the way so many people perceive him to be. then the bull rope (thats the rope the rider is holding on to) falls off. Then he'll really settle down. Bulls aren't dumb. They've learned to associate that rope with a cowboy on his back. If he gets rid of one, he gets rid of the other. therefore he stays a little bit wound up until both are off. As soon as he gets calm where is the first place he is trying to go? Out of that arena. Its big, scary, loud, and really bright. They're outside all night with other bulls close and then led up a dark allley way to a chute. In the chute they're still pretty shadowed by all the people around it. Once you throw them out into that arena with someone on their back, they're intimidated, confused and want the hell out of there. They know they get out of there by throwing the cowboy off and kicking free of the rope. Even the best bulls won't buck if there is no environment change. I've seen rodeos fail because of the way bulls were held before entering the arena. They know what the arena is and how to get out of it.