If you get a call saying you won a sweepstakes you didn’t enter, hang up. (Hocus Focus Studio/Getty Images)

I trust that you’re familiar with that Monopoly “Community Chest” card that reads “Bank error in your favor. Collect $200.” It has a drawing of Rich Uncle Pennybags wheeling back on his heels, so surprised is he at his windfall.

Windfall. We all want one. We want one so badly that our eagerness — I won’t call it greed — can blind us to certain pesky realities.

And it is in the darkness of that wishful thinking that scammers do their work.

Last month, a Takoma Park man I’ll call Raoul (he didn’t want me to divulge his real name), received a phone call from someone purporting to be from the American Sweepstakes Network. It was Raoul’s lucky day, the caller, who identified himself as David Carter, said. Raoul had won $4.5 million and a new car.

Raoul was in the mood for such news. He told me that he had been expecting payment for some work he had done, payment that was late in coming. Perhaps that had put him in an accepting mind space. He confessed that at first he thought it was true.

Carter’s patter was impressive: informative and businesslike. (Raoul tape-recorded some of it.) A team wanted to deliver Raoul’s prize that very day. Because of the great sum involved, an armed guard would accompany the team. They would bring a camera crew and balloons — but only if Raoul didn’t mind. When Raoul said he didn’t really need a new car, Carter said that was fine. They would auction it and add the cash equivalent to his prize.

There was just one other matter: Carter said the tax on Raoul’s prize was $755. This amount would need to be given to the delivery team. A personal check was not sufficient. Too much scamming, Carter explained. (A nice touch, I think.) Raoul was instructed to go to a Walgreens, Rite Aid or CVS and purchase a MoneyPak card in that amount.

That’s when Raoul started to suspect something. He told Carter that he needed to reschedule the prize delivery date and would call him back. Carter gave Raoul a telephone number with a 509 area code and his personal ID number.

Raoul called the Takoma Park police instead. They visited and told him that there wasn’t much they could do because Raoul hadn’t actually been defrauded.

How would the scam have worked? I doubt a prize team would have descended on Raoul’s house, though the promise/threat of an armed guard does give one pause. I suspect that Carter would have telephoned and asked Raoul for the 14-digit access code on his MoneyPak card. With just that number, the scammers could have transferred the $755 to their account.

The New York Times recently reported that the company that makes the MoneyPak cards is putting safeguards in place that will make it harder to use them in fraud. Other cards, however, may not be as scam-proof.

“They were pretty darn sophisticated,” Raoul said of the people he’s sure wanted to take his money.

It bears repeating that it is very unlikely that someone will call you out of the blue and tell you you’ve won a sweepstakes or are entitled to free money from the “U.S. Government Grants Department.” No, check that. It’s unlikely that someone who calls and says that will be legitimate.

You can get information on some of the current scams out there by visiting the Federal Trade Commission’s consumer Web site at www.consumer.ftc.gov/scam-alert.

I called the 509 number that Raoul was given and got a garbled recorded message. (It sounded like it said, “You have reached Mega Mainlines.”). The machine wasn’t taking messages, but an hour later, I got a call back from a number that came up “No Caller ID” on my cellphone’s display.

I recognized the voice from Raoul’s recording. I asked if this was David Carter. He said it was. I said I was a writer at The Washington Post and wanted to talk about American Sweepstakes. He said someone would call me back. When I insisted that I wanted to speak with him, he said: “How do I know who you are? Would you like me to call the FBI about you?”

I said I’d be delighted to talk to the FBI.

Please, people. Be skeptical.

Twitter: @johnkelly

For previous columns, visit washingtonpost.com/johnkelly.