The Cup of Confucius (fig.), here on display in the Tan Ky Merchant House in Hoi An, is the Asian version of a Tantalus Cup and can only hold liquid if it is partially full.

It works on the principle of communicating vessels and has a hidden syphon. When filled to the top, the liquid will spill out of the bottom of the cup, hence it is also known as Greedy Cup.