Satire joke via web - What's the catch?

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The Devil tells a Real Estate Agent, “Look, I can make you richer, more famous, and more successful than any Real Estate Agent alive. In fact, I can make you the greatest agent that ever lived.”

“Well,” says the Real Estate Agent, “what do I have to do in return?”

The Devil smiles, “Well, of course you have to give me your soul,” he says, “but you also have to give me the souls of your children, the souls of your children’s children and, as a matter of fact, you have to give me the souls of all your descendants throughout eternity.”

“Wait a minute,” the Real Estate Agent says cautiously, “What’s the catch?”
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