its in horse racing. There are three main races that make up the Triple Crown: Kentucky Derby, Preakness Stakes and the Belmont Stakes. If one horse wins all three races there are the Triple Crown winner, thus deemed the best horses in horse racing. No horse has been able to pull it off since Affirmed in 1979. Big Brown won both the Kentucky Derby and the Preakness, but unfortunately he came in 9th at the Belmont (which was today). Its a shame too, he seemed like he was going to pull it off too!
**edit, Affirmed won it all in 1978.
No hour of life is wasted that is spent in the saddle. ~Winston Churchill