A place where high-pressure salespeople use banks of telephones to call
lists of potential investors (known as a "sucker lists") in order to
peddle speculative, even fraudulent, securities. A boiler room is called
as such because of the high-pressure selling.
A broker using boiler-room tactics gives customers only positive
information about the stock and discourages them from doing any outside
research. Boiler-room salespeople typically use catchphrases like "it's a
sure thing" or "opportunities like this happen once in a lifetime".