KEEP OFF THE DIRIGIBLE PLUMS
-- Sign in front of the Lovegood's House (DH20)
Dirigible plums are a small orange fruit growing near the Lovegood house.
dirigible = shaped like an airship or flying blimp
dirigible = an airship comprised of a large, gas-filled cylindrical tube with a carriage beneath. In the film, the dirigible plums are shown floating in the air in (DH1/f), which harkens to the meaning of the word.