Guy walks into a bar. He sees a jar full of twenty dollar bills. He asks the bartender what it's for.

"I have a horse in the stable behind the bar. You put in twenty bucks and try to make my horse laugh. If you make him laugh, the whole jar is yours but if you fail then you're out twenty bucks."

So the guy puts in twenty, goes to the stable and a minute later the horse is laughing hysterically. Guy walks back to the bar and without saying a word to the bartender, who has a stupefied look on his face, takes the jar of twenties and leaves.

A year later the same guy comes back to the bar and sees another jar full of twenties. He asks the bartender what it's for this time.

"Well, ever since you came in here last year, my damn horse hasn't stopped laughing. You put in twenty bucks and if you can make him stop laughing the jar is yours."

The guy puts in another twenty and goes to the stable. A minute later, dead silence. Not a sound from the horse. Guy walks back and picks up the jar. As he's about to leave, the bartender says "Hey wait a minute. You gotta tell me how you made my horse laugh and stop laughing when everyone else couldn't do either."

The guy says "The first time I told your horse that my dick is bigger than his. The second time I proved it."