Someone who pretends to be a customer to help sell something, often secretly working for the seller.
The actor was a shill for the company, promoting their products without people knowing.
A person who helps in a trick to attract people to a place or event, often to make them spend money.
The street performers had a shill in the crowd who would pretend to be amazed by their tricks.
To work as a shill, promoting something in a dishonest way to make it seem better than it is.
He was caught shilling for the fake investment scheme, trying to convince others to join.