"I do like sour candy except sour milk. Yuck."
This has nothing to do with sour candy, especially sour milk. A sour horse is when a horse doesn't like something. A ring sour horse, also known as arena sour horse wouldn't want to be in the ring or the arena. A gate sour horse is when they refuse to enter a gate. A buddy sour horse is when they don't want to leave their friend. Herd sour is when a horse doesn't want to leave the herd. Barn sour is when a horse refuses to leave or go into a barn. Horses don't have a barn, though, because we don't say stable sour or stall sour.
