A tramp walks into a bar and demands a drink. He is refused because he clearly can't pay.
The tramp then pulls a hamster from his pocket and says, "In return for the drink, I'll show you something you've never seen before" He takes the hamster over to the old piano in the corner where it proceeds to play Gershwin tunes beautifully.
The barman is impressed and pours out a scotch for the same tramp, who knocks it back and demands another. "No way" says the barman. "Show me another miracle and you can have another. Otherwise get out."
From another pocket the tramp produces a frog which starts to sing beautifully. Another customer is so impressed that he immediately offers the tramp £500 for the frog, which he accepts gratefully.
The barman is amazed, "You're mad," he tells the tramp, "That frog must have been worth millions." The tramp smiles and orders another scotch. "Not a bit of it," he says, "The hamster is also a ventriloquist."