I Literally Just Told You
(My store hands out this cash coupon where if you spend a certain amount in a previous purchase you get a certain dollar amount off your purchase on a selected weekend in the future. During that weekend if you didn’t receive a cash coupon we send out a regular 15% off your purchase coupon to use. Neither can be combined.)
Customer: “Ugh, how do you know it’s not combinable!?”
Manager: “Well, I’m literate and read the back of the coupon where it says it can’t be combined with any other discount.”