Do you have a friend who is too greedy and pour wine over the limit. Then you should gift him the Greedy cup or Pythagorean cup
Pythagorean cup or Greedy cup, Tantalus cup is a device in a form of a drinking cup. When it is filled beyond a certain point, a siphoning effect causes the cup to drain its entire contents through the base.
A Pythagorean cup looks like a normal drinking cup, except that the bowl has a central column in it. The central column of the bowl has a hole at the bottom of the stem. A small open pipe runs from this hole almost to the top of the central column, where there is an open chamber. The chamber is connected by a second pipe to the bottom of the central column, where a hole in the column exposes the pipe to (the contents of) the bowl of the cup.
When the cup is filled, liquid rises through the second pipe up to the chamber at the top of the central column, following Pascal’s principle of communicating vessels. As long as the level of the liquid does not rise beyond the level of the chamber, the cup functions as normal. If the level rises further, however, the liquid spills through the chamber into the first pipe and out the bottom. Gravity then creates a siphon effect through the central column, causing the entire contents of the cup to be emptied through the hole at the bottom of the stem. Some modern toilets operate on the same principle: when the water level in the bowl rises high enough, a siphon is created, flushing the toilet.
The special thing about this cup is that it can be used as a normal drinking cup as long as it is only filled with a certain amount of fluid. If a person is too greedy thought and fills it over the limit, the entire content will empty through a hole in the bottom of the cup. It is named after the famous Ionian Greek philosopher Pythagoras of Samos, you might know him from the Pythagorean Theorem.
Source: Pythagorean Cup