A game warden finds an man at a popular trout fishing spot with two dozen trout swimming in a bucket. "That's way over the limit," he says. "You're under arrest."
"But officer, please," the man says, "these are my pet fish from home. I just bring them down here to let them swim free once a week. When I whistle, they all come back and get into the bucket to go home."
"I don't believe it," says the warden. "Show me."
The man promptly dumps the trout into the stream and gazes after them as they swim away.
After a minute, the warden says, "OK, how long?"
"How long what?" says the man.
"How long till you call the fish back?"
"What fish?"