»lagniappe

This San Francisco Chronicle story on the 30th birthday of casual carpool uses a bit of creole vernacular, lagniappe, the origin of which I couldn't discern. According to this etymology , the word originates in Quechua (!!):

      n. Chiefly Southern Louisiana & Mississippi.
A small gift presented by a storeowner to a customer with the customer's purchase.
An extra or unexpected gift or benefit. Also called boot. See Regional Note at beignet.

[Louisiana French, from American Spanish la ñapa, the gift : la, the (from Latin illa, feminine of ille, that, the) + ñapa (variant of yapa, gift, from Quechua, from yapay, to give more).]

REGIONAL NOTE   Lagniappe derives from New World Spanish la ñapa, “the gift,” and ultimately from Quechua yapay, “to give more.” The word came into the rich Creole dialect mixture of New Orleans and there acquired a French spelling. It is still used in the Gulf states, especially southern Louisiana, to denote a little bonus that a friendly shopkeeper might add to a purchase. By extension, it may mean “an extra or unexpected gift or benefit.”

I would have written boon or perhaps convenience. But lagniappe is one of those rare words in American English that has a deeply regional flavour.

The note for beignet reads:

      REGIONAL NOTE   New Orleans, Louisiana, has been a rich contributor of French loan words and local expressions to American English. Many New Orleans words, such as beignet, café au lait, faubourg, lagniappe, and krewe, reflect the New World French cuisine and culture characterizing this region. Other words reflect distinctive physical characteristics of the city: banquette, a raised sidewalk, and camelback and shotgun, distinctive architectural styles found among New Orleans houses.