Lagniappe

[lan-yap, lan-yap] /lænˈyæp, ˈlæn yæp/

noun
1.
Chiefly Southern Louisiana and Southeast Texas. a small gift given with a purchase to a customer, by way of compliment or for good measure; bonus.
2.
a gratuity or tip.
3.
an unexpected or indirect benefit.
/lænˈjæp; ˈlænjæp/
noun (US)
1.
a small gift, esp one given to a customer who makes a purchase
2.
something given or obtained as a gratuity or bonus
n.

“dividend, something extra,” 1849, from New Orleans creole, of unknown origin though much speculated upon. Originally a bit of something given by New Orleans shopkeepers to customers. Said to be from American Spanish la ñapa “the gift.” Klein says this is in turn from Quechua yapa “something added, gift.”

We picked up one excellent word — a word worth travelling to New Orleans to get; a nice, limber, expressive, handy word — ‘lagniappe.’ They pronounce it lanny-yap. It is Spanish — so they said. [Mark Twain, “Life on the Mississippi”]

noun

A dividend; something extra: I hit her with a few real hard ones for lagniappe (or good measure)/ From the company’s point of view, of course, safety is a lagniappe

[1849+; fr New Orleans Creole, origin unknown and much speculated upon; originally a little present or gratuity given to a customer by a New Orleans merchant]