Gassy Loophole
Lots of banks offer perks like cash back, points, and other rewards on their cards. For this OP, it was a 3% cashback points on the purchase of gas. While it’s a pretty great offer on its own considering the price of gas, the OP found a way to make the deal even sweeter.
They discovered that the offer worked even when they combined it with other purchases so they used it to buy $1 worth of gas along with cartons of cigarettes to get a discount. This is perhaps not the healthiest way to exploit a loophole but it did work so there’s that.