door knocker
n.β Β«Officer Kushner did not find anyone at home.…Officer Kushner left a βdoor knockerβ at the home requesting that defendant contact him regarding a complaint about the care and feeding of her animals. He also left several telephone messages for her.Β» βby North Carolina Court of Appeals Calloway v Onderdonk, No. COA02-1076 (Buncombe County) July 1, 2003. (source: Double-Tongued Dictionary)