a little something extra, something given for good measure
We picked up one excellent word, wrote Mark Twain in Life on the Mississippi (1883), “a word worth traveling to New Orleans to get; a nice limber, expressive, handy word-‘lagniappe’…. It is Spanish-so they said.”
Twain encapsulates the history of “lagniappe” quite nicely. English speakers learned the word from French-speaking Louisianians, but they in turn had adapted it from the American Spanish word la ñapa. Twain went on to describe how New Orleanians completed shop transactions by saying “Give me something for lagniappe,” to which the shopkeeper would respond with “a bit of liquorice-root, … or a spool of thread.”
” It took a while for “lagniappe” to catch on throughout the country, but by the mid-20th century, New Yorkers and New Orleanians alike were familiar with this “excellent word.” ~Merriam-Webster.com