The 'Liking' Principle in User Interface Design (Jennifer Cardello)

A classic example of the liking principle is the old-fashioned Tupperware party (with its modern counterparts: the kitchen-gadget, jewelry, or wine-tasting party). The host of a Tupperware party was supposed to invite friends and acquaintances at her home and show them a variety of Tupperware containers. The guests could buy these and the host would receive a commission for all containers sold. Initially, the products were sold only via retail outlets, but they didn’t do well. In the late 1940’s, Tupperware began organizing “demonstration” parties. (nngroup.com)