Why don't grocery store coupons ever expire on the day you remember to bring them?

I clipped a dollar off pasta sauce three weeks ago. Stuck it right on the fridge with a magnet shaped like a cow.

Today I actually remembered to bring it—walked down aisle six feeling like a budgeting superhero, sauce in hand, coupon at the ready.

Punchline

Expired yesterday.

Now it lives in my wallet as a bookmark and a reminder that optimism has a shelf life shorter than milk.