Quoted from Scorch:

Have you contacted the buyer directly?
I once bought some pinball items and the next day I found a fraudulent charge from a day or two earlier. Fast forward 2 weeks and I find out that the card company cancelled all transactions after the fraudulent charge including my legit purchase. I only found out because I paid with PayPal and they froze my account until I straightend it out.
So while it may be a scam it sounds like it could also b an honest mistake

Quoted from o-din:

You can't trust anybody, not even relatives.
Money Order is a safe, clean method of payment, and once it's cashed, it's a done deal.

The mistake was using a credit card to pay for food at McDonalds. The more you flash that plastic around, the more it is bound to be compromised. Why anybody uses a credit card for small in person purchases is beyond me.

Quoted from Magic_Mike:

Maybe because the bigger crime was you eating at McDonald's.