knock-and-talk

knock-and-talk
 n.— «A knock-and-talk search works like this: Police officers go to the door of a residence in which they suspect illegal activity is occurring. They knock, introduce themselves as a police officer, and ask to come in and talk. If the resident says yes, they enter the home and look around for signs of drugs or illegal alcohol. If they see any, they detain the resident(s) in the dwelling while calling for a warrant that allow them to legally search for the evidence they saw during the visit.» —“Watch out for knock-and-talks” in University of Iowa Daily Iowan (Iowa City) Sept. 19, 2005. (source: Double-Tongued Dictionary)