It Ain't Hay (1943)

"THEY'LL GIVE YOU THE "HOARSE" LAUGH...when I give THEM the laugh-laugh! A Fun-Hit You Can Place Your Money On to Win"

Abbot and Costello must find a replacement for a woman's horse they accidentally killed after feeding it some candy. They head for the racetrack, find a look-a-like and take it. They do not realize that the nag is "Tea Biscuit," a champion racehorse.