I sell wine on the phone. One day, I convinced a particularly difficult individual to purchase some rather expensive wine - a gentleman who told me he has never once given his CC info over the phone. I feel proud of myself.
Fast forward 6 hours later. It is 6:45, and I am about an hour from clocking out, having a glass of wine, and going home. The same gentleman calls me back, and says that AMEX had called to inform him that charges were placed at a gas station in Canada after he had given me his card number. As I am very far away from Canada, I kept my cool, got him off the phone, and took the issue to my superiors who instructed me to follow up in the morning.
The next morning, I called him. He proceeded to tell me that he had "Just been fucking with me" and that I am a "real sport".