Okay, so this one isn't a guaranteed freebie. But they are giving away 250,000 Twix Bars over the next couple of weeks, and you can play the game once per day. I played and won a free bar on my first try. Try a couple of days and your bound to win at least one. You don't need a special code to play, just click the "don't have a code" button once you get to that point.