A man walks into a bar and sees a sign that says "Free drinks for anyone who can make the horse at the end of the bar laugh."
So the man goes up to the horse and whispers something in its ear. The horse starts laughing hysterically, rolling on the ground and snorting with joy. The bartender is amazed and gives the man a free drink.
The man comes back the next day and sees a new sign that says "Free drinks for anyone who can make the horse cry." So he goes up to the horse and whispers something else in its ear. The horse starts sobbing uncontrollably, tears streaming down its face. The bartender is once again amazed and gives the man another free drink.
On the third day, the man walks in and sees a new sign that says "Free drinks for anyone who can make the horse stop laughing and crying." The man goes up to the horse, whispers something in its ear, and the horse stops laughing and crying, looking completely confused.
The bartender is utterly dumbfounded and asks the man, "What did you say to that horse to make it laugh, cry, and stop doing both?"
The man replies, "Well, the first day I told him my penis was bigger than his. The second day I showed him that I was right. And on the third day, I proved it to him by showing him how much I've spent on free drinks!"