Two racehorses are standing in adjacent stalls. One says to the other, "You know, the weirdest thing happened yesterday. They were getting me saddled and ready to go out when something bit me in the behind. Really hurt, too, but I didn't have time to figure it out because it was time to go. And I won the race at 15-1!"
The other horse replies, "That's really spooky because I had the same experience about a month ago. Just like you, I was in here getting ready when something stung me, hard, on the backside. And like you, I couldn't do anything about it because I had to go out and run. And I ran the best race of my life!"
A dog is walking past and happens to overhear the conversation. He fixes the horses with a contemptuous look and says, "You idiots—they were doping you! They were giving you performance drugs to make you run faster!"
Upon which one horse turns to the other and says in an astonished voice, "Jeez, did you see that?!? A talking dog!!"