The Simpson kids build a fort from boxes, with a l.o.t.r. homage
The battle sequence with Bart, Lisa, and the box salesmen uses The Fields of the Pelennor, a portion of the score from the The Lord of the Rings: The Return of the King, and the scene itself is a parody of the Battle of the Hornburg from The Two Towers and the Battle of the Pelennor Fields from The Return of the King. Lisa also references the movie when she says to Nelson "you've come to help us in our hour of need." One of the A.S.S. delivery men even flies a fell beast like the Nazgûl. Lisa also says "So it begins" as the enemy attack begins, as King Théoden says before the Uruk-hai attack Helm's Deep. see http://en.wikipedia.org/wiki/Rome-old_and_Juli-eh for more info. Best line has to be who know guys in brown shirts could be so much trouble