Spiff

A spiff is a small, immediate bonus for a sale.

There is a reference to a spiff in a slang dictionary of 1859: “the percentage allowed by drapers to their young men when they effect sale of old fashioned or undesirable stock”. It seems to be connected with the use of the word in that period to mean a dandy or somebody smartly dressed (hence spiffy, and to spiff up—to improve the appearance of a place or a person), but nobody seems to have been able to disentangle the threads of which came first, or what influenced what, or where the word originally came from.

See also

Spiff is also the English translation of French cartoon anthropomorphic dog character "Pif" created by José Cabrero Arnal for a communist newspaper. See Spiff and Hercules.