something extra, something for good measure n. Pronounced lan-yap.
--I Always Look Up the Word Egregious, Maxwell Nurnberg
This word was born in the United States among the Creole population of Louisiana. It's original meaning is seen in this sentence written by a traveler in 1893 in Harper's Magazine:
"'Take that for lagniappe,' says a storekeeper in New Orleans as he folds a pretty calendar into the bundle of stationary you have purchased." (Nurnberg)
Bloggin' John Comments
When using the word to explain your motive for offering a gift, say "That's for lagniappe" or "Take this for lagniappe," rather than adding an article in front of the word, as in "I want to give you a lagniappe." That little smidgin of an a would tag you right off as a visitor from the north.
If, by the way, you're not quite sure about the meaning of the final word in the title of Maxwell Nurnberg's book I Always Look Up the Word Egregious, you'll find that The Little Oxford Dictionary defines egregious as "extremely bad." I've quoted the LOD's definition of egregious here, not out of necessity, but, rather, for lagniappe.