door knocker
n.— «If you are not at home at the time of delivery, it is common practice for the delivery driver to leave a “DOOR KNOCKER” with instructions for alternate arrangements of your package.» —“Flexible Learning Distance Education” University of Windsor Bookstore (Ontario, Canada) Feb. 21, 2007. (source: Double-Tongued Dictionary)
Further reading
Linda in Salisbury, North Carolina, wonders why boxing is called the sweet science, since there’s nothing obviously sweet about a bruising sport. This term took hold among British sportswriters in the early 19th century as promoters tried to frame...
Paul in Batavia, New York, recommends The Door-to-Door Bookstore (Bookshop|Amazon), a novel by Carston Henn, translated from German by Melody Shaw, which includes a wonderful description of a book with a perfect final paragraph that you nevertheless...