Brownie points are a hypothetical social currency, which can be accrued by doing good deeds or earning favour in the eyes of another, often one's superior. The origin of the term is uncertain.
A popular, but unproven, etymology is an allusion to the merit badges obtained by junior girl scouts (Girl Guides) for carrying out good deeds. Baroness Olave Baden-Powell (wife of their founder, Robert Baden-Powell) named the Brownies after a kind of mythological elf that does helpful things around the house. It has been suggested that the term was given impetus though its coincidence with related scatological slang, see below .
Another proposed etymology is that the term derives from the name of a 19th century American railroad superintendent, George R. Brown who, in 1886, devised what was then an innovative system of merits and demerits for railroad employees on the Fall Brook Railway in New York state. Accounts of his system were published in railroad journals, and adopted by many leading U.S. railroads. American railroad employees soon began referring colloquially to "brownie points", and at some point, the term entered the general vocabulary.
In the 1930s, The Curtis Publishing Company, published several magazines, including the Saturday Evening Post and the Ladies Home Journal. These magazines were distributed to subscribers through a delivery network that used youths, primarily boys, to go around to the individual houses. The boys received a small commission, but in return for meeting certain sales targets, they could also receive company scrip, comprising green and brown vouchers. These vouchers were usually known as "greenies" and "brownies". Five greenies equalled one brownie. The greenies and brownies could be redeemed against goods from the company's catalogue.
The Oxford English Dictionary conjectures that this expression could also have derived from U.S. military slang for sycophants, "brownnosers", while mentioning the less-likely but popular etymology that derives it from the awards system of the Brownies Girl Guides/Girl Scouts. "Brownie" itself in the sense of "brown-noser" was in use in the 1940s.
The OED reports its first appearance in print as 1963, though the origins of the phrase predate this. Its frequent appearance in newspapers in the 1950s date back to the earliest known usage in 1951, where a man in the Los Angeles Times speaks of earning favor with his wife in terms of brownie points.