A McDonald's customer has explained why you should always keep hold of your receipt.
And while it's probably the last thing on your mind when you're stuffing your face with chips, the little slip of paper could save you some money.
Posting a photo on the Extreme Couponing and Bargains Facebook page, one thrifty diner explained how keeping the receipt could get you a cut price Big Mac and fries.
They said: "MCDONALD'S HACK. Don't throw your receipt and use it for the discount. I always keep Mcd receipts in my wallet for use it in the future.
"Doing the survey doesn't take more than 2 mins.
"£1.99 for Big Mac + medium Fries (yes you have option to change the burger). Sometimes I change it to Quarter Pounder. Big Mac + Fries without receipt= £3.09 + 1.19 = £4.28. With receipt = £1.99 You save £2.29
"If you and your partner use same hack (yes you need 2 receipts on separate orders) you can save £2.29 x 2 = £4.58. Enjoy!!"
And if you fancy a late night snack, we have more good new, as McDonald's announced that its restaurants would be staying open past the curfew that was introduced last week.
As of Thursday (24 September), all restaurants and pubs have to close their doors at 10pm in an attempt to stop the current upward trend in coronavirus cases, but McDonald's is allowed to remain open past that as the company can offer drive-thru and delivery services.
Announced earlier in the week by Prime Minister Boris Johnson, the new rules state: "Businesses and venues selling food for consumption off the premises, can continue to do so after 10pm as long as this is through delivery service or drive-thru."
So, while you won't be able to sit in the restaurants, McDonald's will still be able to maintain its regular opening hours - 24 hours each day, in some cases - where other restaurants will have to shut.
McDonald's UK and Ireland CEO Paul Pomroy confirmed: "With thanks to our delivery partners Uber Eats and Just Eat, more than 800 restaurants will also be offering McDelivery past 10pm."
However, Mr Pomroy went on to say that the chain would be looking closely at the rates of infection in certain areas, as well as local lockdown restrictions, and might end up closing some of its locations down if the number of coronavirus infections is too high.
He added: "We will be guided by local and national government regulations."