The title of the episode, refers to phrase touted by Utilitarian philosophers and its founder Jeremy Bentham, in their maximizing of happiness calculations, namely, an action is good if a great number of people benefit from said action.
A "numbers station", is essentially a radio station which literally broadcast a string of numbers ,or other seemingly random information to the untrained ear. In the Cold War, it was a means by which the security services of a state actor could discreetly convey coded information to intelligence operatives in the field. With respect to the episode, the Mexican Field Agent, hijacked the radio channel to piggyback his own particular message with his "butt set".