What is "mamihlapinatapai"

n. A situation in which all participants want something to be done, but none want to do it.

The word Mamihlapinatapai (sometimes spelled mamihlapinatapei) is derived from the Yaghan language of Tierra del Fuego, listed in The Guinness Book of World Records as the "most succinct word", and is considered (for example by Austrian playwright Clemens Berger) one of the hardest words to translate.