What looks like an ordinary cup is actually a practical joke waiting to happen and it was invented by none other than Pythagoras.
We may know a lot about the ancient Greeks but one thing that most people tend to overlook is the fact that they were people, just like you and me. They liked to cut loose every once in a while and they even had a practical joke in the form of an ordinary cop that would be great for parties. Believe it or not, it was invented by the Greek philosopher and mathematician, Pythagoras. Most people know him because of the Pythagorean theorem from geometry class, but it seems as if he had a playful side as well. Just take a look at the ‘Cup of Justice’ and you will see what I mean.
The cup looks perfectly normal but if you fill it too far, all the liquid is siphoned through a hole in the bottom. Imagine having this at a party. Somebody attempts to pour too much drink into their cup and before you know it, they have a lap full of liquid. It uses gravity and atmospheric pressure to pull off the gag flawlessly.
When you look closely at a cross-section of the Pythagoras cop, you will see how it works. There is a hidden channel that comes up through the center column and when liquid is poured into the cup, it makes its way to the top of the channel. As long as the person stops soon enough, it will not be a problem but if they put too much in the glass, the pressure causes the liquid to siphon out of the cup and spill through the bottom.
You can buy these cups in Greece, where they are known as o kounenos tis dikaiosynis (the Cup of Justice). If you don’t happen to live in Greece, you can always buy them on Amazon.
You can also watch the magic happen in this video: