Bottomless cup of soft drink for life

Next time you are at Hungry Jacks or Burger King and get given a cup to fill at the self-service drink station, fill the cup to the brim with your favourite soft drink (No ice if you really want to get more soft drink for your dollar, but more diabetes for your dollar as post mixes are very sweet). Then when you've finished your drink, take the cup with you and come back whenever you feel like a soft drink and refill from the machine. You won't get caught as long as you use the cup with a corresponding logo in the same restaurant. You can do this as many times until there is a hole in the bottom of your cup! How's that for a super cheap thought?