Pronoun used by royalty to indicate that they represent both the body natural and the body politic*. Thus, the usage of the personal pronoun 'we'.
*the collective body of a nation or state as politically organized with the king/queen being viewed as the head, the peasantry being viewed as the legs etc.
1. "So, we were riding our bike to school today when we ran into this old bum and this cop pulled us over, but we told the cop we were going to be late for school so let let us go."
"Dude. there's only one of you."
"We know."
2. "Hmm... we seem to have left the door unlocked again, haven't we?" <WHACK!> "Maybe that'll teach us a lesson, hmm?"