YaghanMamihlapinatapaiTwo people looking at each other, each wishing that the other will begin an action that they both desire but are unwilling to suggest or begin themselves.

http://en.wikipedia.org/wiki/Mamihlapinatapai Supposedly "the most succint word in the world" and "one of the hardest words to translate." A couple of years ago I was lucky enough to share an evening with the last native speaker of this dying language, before I knew about this word.