A man walks into a bar and sees a sign that says, "Free drinks for life if you can make the horse laugh." Intrigued, the man asks the bartender about the sign.
The bartender explains, "We have a horse out back who hasn't laughed in years. If you can make him laugh, you'll get free drinks for life."
The man decides to give it a shot and goes outside to see the horse. He whispers something in the horse's ear and, to his surprise, the horse starts cracking up laughing. The man walks back into the bar and the bartender says, "Well, I'll be damned! How did you do it?"
The man replies, "Oh, it was easy. I just told him I have a bigger dick than he does."
The bartender laughs and says, "Well, I guess we have to honor our agreement. Free drinks for life for you!"
The man starts drinking happily, but the bartender can't help but ask, "But I have to know, what did you really say to the horse?"
The man chuckles and says, "I told him my wife is sleeping with a donkey."