Context

This famous line is spoken by Katharine Hepburn as Eleanor of Aquitaine in The Lion in Winter (directed by Anthony Harvey, 1968). 

King Henry II has everyone out to get him, from his wife, Eleanor of Aquitaine, to this three sons, Richard, Geoffrey, and John. The boys fighting over their father's throne leads to squabbling amongst themselves...which gets them nowhere.

When John whines that his brother has a knife, his mother, exasperated, says, "Of course he has a knife, he always has a knife, we all have knives! It's 1183 and we're barbarians!"

Where you've heard it

Maybe you've heard it while wielding pointy objects at your brothers. Or maybe during one of the two film adaptations, the first of which was Anthony Hopkins's first film role and starred Katharine Hepburn, an actual descendant of Eleanor of Aquitaine.

Pretentious Factor

If you were to drop this quote at a dinner party, would you get an in-unison "awww" or would everyone roll their eyes and never invite you back? Here it is, on a scale of 1-10.

Barbarians calling for world peace is a little pretentious, and this line is awfully self-aware.