Some race horses in a stable were chatting, and one of them said, "I've won eight out of my last 15 races!" Another horse broke in, "Well, in my last 27 races, I've won 19!!" At this point, they noticed that a greyhound dog had been sitting there listening. "I don't mean to boast," said the greyhound, "but I've won 88 of my last 90 races!" The horses were clearly amazed.
and the punchline is ...
"Wow!" said one of the horses. "A talking dog!"