Used in sales environments to give the associates extra incentives. Double spiffs are usually given out at the end of a month, quarter or year and sometimes special occasions.
Jason: Dude---I wrote 8 deals today!!!
Yamilin: Sweet---You got some serious double spiffs as today is the last day of March.
Jason: I hope none of them cancel.
Yamilin: Don't jinx it. They will stick.