spiff
n.— «Does Staples have a chance? You bet, because they have thousands of people walking into their retail stores every hour, giving them a huge customer base to contact. Although their Staple Business Advantage program for office products tends to be a little low profile, they’re out there, they’re providing more than just office supply catalogs to small businesses, and Business Advantage salespeople get a spiff (euphemism for financial incentive) to help sign up Network Services customers.» —“Two new support options for SMBs” by James E. Gaskin NetworkWorld Sept. 25, 2008. (source: Double-Tongued Dictionary)
“Spiff” was in common use when I worked in retail (late ’70s to early ’80s, Sam Ash Music stores, NYC). It referred to a small bonus (a dollar, typically) for selling a specific brand or item that the store made a higher level of profit on. If you could switch a customer from a brand name to a store brand you’d get a spiff.