Every so often the cash register gods at Starbucks randomly choose people to take part in an online survey. They give you the chance to win a nice little Starbucks gift card as a prize if you're selected from those who participate in the program.
One day, the gods favoured me and I decided to take a few minutes to take the survey. What I wasn't expecting was to actually get a free drink order out of it.
At the end of the survey I was told to write a specific code on my original receipt and exchange it for the beverage of my choice. I was content with the chance of winning the prize, so the unexpected free beverage totally made my day.