Scammers are always trying to figure out a way to separate travelers from their money, including this technique which involves a middle-of-the-night call to your hotel room.
The bad guys phone when you are sound asleep, say they work at the front desk of your hotel and that your credit card payment at check-in didn’t go through…will you please give them the numbers again.
It’s middle of the night, your brain is still half-asleep, so you comply. As soon as they have your number they begin charging things to your card.
Of course, you can call the credit-card company and reverse all these charges, but you may not know you’ve been scammed until you receive the bill back at home.