Near the conclusion of the Great Movie Ride, you visit the Munckin Village from "The Wizard of Oz" (1939) but before you can follow the Yellow Brick Road, you must confront the Wicked Witch of the West. In doing so, Disney Imagineers have the Cast Member tour guide quickly perform a scene from the film.
On the ride, the Wicked Witch of the West appears and demands to know who killed her sister, the Wicked Witch of the East. The Cast Member tour guide claims the killing was an accident, (something Dorothy says in the film) but when the Wicked Witch of the West threatens the tour guide and your group, the tour guide recites a line from the film.
Wicked Witch: Well, my little pretty, I can cause accidents, too!
Tour Guide: Oh rubbish, you have no power here. Be gone before someone drops a house on you, too.
So while the line the Tour Guide delivers can seem a little campy or corny depending on who's delivering it, it does have meaning to the film and now you know why it's there.