One definition is
"A shill or plant is a person who helps another person or organization to sell goods or services without disclosing that he or she has a close relationship with the seller. The shill pretends to have no association with the seller/group and gives onlookers the impression that he or she is an enthusiastic independent customer."
"A shill or plant is a person who helps another person or organization to sell goods or services without disclosing that he or she has a close relationship with the seller. The shill pretends to have no association with the seller/group and gives onlookers the impression that he or she is an enthusiastic independent customer."