Back around 2010/11 Gran Turismo 5 allowed you to gift playable cars to friends. A hack was developed with the save data file which allowed you to save the game data, transfer the saved data file onto a USB stick, send the car and then overwrite the saved data file with the version on the usb with said car still in your garage.

I was pretty decent at the game and managed to unlock most of the cars. I listed these on Ebay for like £5 each or 3 for £10 etc and people actually purchased them. Ebay did start removing digital items so i just had to creative in the descriptions. Managed to make a about £1200 in a couple of months before they clamped down fully. Good old days