There are a lot of videos on the Internet on how to hack Coke machines to get a free Coke or something else ( who know what?). I will post one more that I found recently. With a supposed secret combination which is the order you push the buttons you can receive some change from that machine.

I don’t know if it works or not but I will try it when I will be near a Coke machine.

I won’t advice you not to try this because it is for educational purposes only because you will try it anyway .