The college kid was cleaning the hallway at Chez Buce this morning when the vacuum began to puff black smoke. Mrs. Buce hied herself off to Sears for a conversation with the appliance salesman.
--Oh, look at this one, I have one at home, it’s wonderful.
--Um hm. Show me how you change the belt.
--Oh, it’s easy. I have one at home.
--So show me.
--Hm. Well, it’s stuck, but as soon as we find the instruction manual, I can show you how it is done. Did I tell you I have one at home?
From an 1859 dictionary (link):
Spiff "The percentage allowed by drapers to their young men when they effect sale of old fashioned or undesirable stock."
I bet the reason this kid had one at home is that the boss laid it on him at a discount to get it off the floor.