Schelling Point... still :)
A Schelling point is a solution that people will tend to converge on in the absence of communication, because it seems natural or 'special' to them.
Ex.: You and a friend have to try to pick the same number from the following sequence:
2, 5, 9, 25, 69, 73, 82, 96, 100, 126, 150
Which number do you pick?