Newcomb's Problem is a thought experiment in decision theory exploring problems posed by having other agents in the environment who can predict your actions.
From Newcomb's Problem and Regret of Rationality:
...A superintelligence from another galaxy, whom we shall call Omega, comes to Earth and sets about playing a strange little game. In this game, Omega selects a human being, sets down two boxes in front of them, and flies away.