A guy walks into a bar with his horse and offers $100 to anybody who can make the horse laugh. Only one guy says he can do it, and he whispers something in the horse's ear. Sure enough, the horse laughs his head off.
So the following week, the guy is back in the bar with his horse again, but his time he offers $200 to anyone who can make the horse cry. The same guy comes up to him, then whispers to the horse and they go off to the bathroom. Amazingly, when they come back, the horse is sobbing. The horse's owner goes over to the other guy, and says: "Hey, I just gotta know - how did you do that?"
"Simple," he replies, "last week I told him I had a bigger cock than him.