"The Hamster" joke

A mangy looking guy who goes into a bar and orders a drink. The bartender says, "No way, pal. I don't think you can pay for it."
"You're right," the guy says. "I don't have any money, but if I show you something you haven't seen before, will you give me a drink?"
"You have a deal, my friend," says the bartender.
The guy reaches into his coat pocket and pulls out a hamster. He puts the hamster on the bar and it runs to the end of the bar, down the side of the bar, across the room, up the piano, onto the keyboard and starts playing Gershwin music. The hamster can really play...
"You're right... I've never seen anything like that before," says the bartender. "That hamster is really gifted."
The guy downs the drink and asks the bartender for another.
"Will that be cash or another miracle, pal?" asks the bartender.
"Watch this," replies the guy. Again, he reaches into his coat again and pulls out a frog. He puts the frog onto the bar, and the frog starts to sing. The frog has a marvellous voice and great pitch. A fine singer.
A stranger from the other end of the bar runs over to the guy and offers him $300 for the frog.
"It's a deal," says the guy. He takes the three hundred and gives the stranger the frog. The stranger runs out of the bar.
"Are you some kind of nut?" asks the bartender. "You sold a singing frog for $300? It could have been worth millions. You must be crazy."
"Not Really, the man replies, "You see, the hamster is also a ventriloquist