Some guy bought a flat-screen TV from a third-party seller via Amazon, and got a rifle instead. [Thanks to Hell in a Handbasket].
The only such screw-up I've ever had myself was once several years ago when I bought an alto sax mouthpiece from some guy on eBay. A few days later I got a large box--so large I had to go to the post office to pick it up, and I'm thinking, WTF? He used this to ship a mouthpiece? It was a cubical box about 15-16 inches on a side. So I open it up, and it's not a mouthpiece. It's a suspended cymbal without the stand, just the cymbal. I emailed the guy and told him he had shipped me the wrong item, and he replied that he hadn't shipped my mouthpiece yet and he didn't know what I was talking about. So, since I couldn't tell by the return postal address if it had come from him or not, I wrote an actual snail-mail letter to the return address saying what happened. A few days later the mouthpiece arrived. I waited a couple of weeks and never got a reply to my letter. So I knew a guy who played drums in a band and asked him if he could use it. He said sure, so I sold it to him for about the same price I paid for the mouthpiece.
So the cymbal paid for the mouthpiece, which means I got a free mouthpiece, but I never did learn how I got the cymbal.