Riddles Random Riddle: 10-28-2016 October 28, 2016August 15, 2016 gags You have a glass of water that looks about half full. How can you tell, only using the glass of water itself, if the glass is half full or not? The glass is a right cylinder. Show answer Tip the glass of water until the water reaches the rim of the glass and if the water lines up perfectly with the bottom rim of the glass, it is half full.