lagnappe

{ , n. [ Also spelled lagnappe. ][ Etym. uncertain. ] 1. In Louisiana, a trifling present given to customers by tradesmen; a gratuity. [ 1913 Webster ]

Lagniappe . . .is something thrown in, gratis, for good measure. Mark Twain. [ Webster 1913 Suppl. ]

2. A tip or gratuity. [ PJC ]

3. Hence: Anything obtained gratuitously or unexpectedly. [ PJC ]