A man wants to buy a horse. So he goes to the horse store, and after browsing for a while, he finds one that he likes. “I'll take that one,” he says to the owner.

The owner frowns. “Well, I'm afraid that horse has a problem. You see, he likes to sit on grapefruit.”

The man gives him a funny look. “Grapefruit?”

“Afraid so. Anytime he sees a grapefruit he goes crazy and just sits down right on it. It's impossible to move him when he gets like that.”

The man thinks for a minute and says, “I really don't think that will be a problem. I don't eat grapefruit myself and I never have it around the farm. So I think I'll just take that horse anyway.”

The man pays for the horse and rides out of the store. On the ride home he comes across a shallow river. Halfway across, the horse lets out a terrific whinny and sits down right in the water. The horse won't budge. Finally, in desperation, the man levaes the horse and returns to the store.

Furious, the man says to the previous owner, “That horse you sold me has a problem!”

“I told you! He likes to sit on grapefruit!”

“But he sat down in the middle of the river! There wasn't a grapefruit in sight!”

The previous owner slapped his forehead.

“Oh, right!” he said. “I forgot to tell you. He likes to sit on fish too."