Walt came up with the term to describe the castle at Disneyland - presumably it refers to holding out a sausage for a dog to draw its attention, but Californians can clarify this.
The original 'story' of Main Street U.S.A at Disneyland was you enter through the lobby of the theater, past the coming attractions posters, then the curtain goes up as you emerge in a busy, bustling street of yesteryear. You're drawn down the street by - what's that - a castle? Out of place, yet fitting in perfectly, it's the thing that draws the eye and encourages guests further into the park.
Every subsequent park has been built with this in mind. Spaceship Earth at Epcot, the Chinese Theater at MGM, Tree of Life at DAK, the castles at Hong Kong, Tokyo and Paris, and the volcano at DisneySea. The only park without a clear weenie is Disney Studios Paris, although the Hollywood hills backdrop sort of serves the same purpose.