Technically, you hold the tray and turn the faucet on to fill with water. Once you have Tetris’d the tray with water, put it in the freezer to unlock Level Cold Drink. You already know what I would recommend you use these amazing pieces of food art to chill, but I have been told it works with non-alcoholic beverages as well. (I can neither confirm or deny the previous statement because it’s just not as much fun to eat Tetris out of a Diet Coke.)
I’m sure there’s some licensing issue that prevents these from being called Tetris Cubes, or Tetricubes, or TetrICE, but I don’t care. This tray makes Tetris a drinking game and you don’t even have to buy (more accurately, find the proper connectors for) a Nintendo. Plus, the tray is flexible food grade silicone and the blocks are easy to remove. It’s almost as easy to buy @ThinkGeek.