A shill is a confidence trickster's accomplice who pretends to be an enthusiastic customer in order to encourage the victim, or mark. ("I can walk!", or "I can see!", or "I'll buy ten!"). The technique employs group dynamics as an element of crowd psychology: the victim comes to feel that he or she stands in good company, has good judgement, and should not miss this opportunity.
The word is probably an abbreviation of shillaber, which has the same meaning, and appeared early in the 20th century from an unknown origin.
Examples of shills
In the case of betting that requires skill, the trickster and shill play out one or more times so that the shill wins and create the impression that it is easy to win.
In marketing, a shill functions as a provider of a testimonial - apparently unsolicited. In sales, the customer reference or the reference site equates to the shill.
In an auction, a shill bid is an anonymous bid placed by the seller in an attempt to raise the price. Shill bids are also used in real estate sales to encourage an offeror to raise the amount of their offer.
The term is also used by illusionistss to describe a collaborator in a magic trick.
One could regard groupies as shills except shills are usually paid for their services.
