The reason McDonald's is so successful all around the world is that you can go to any location and know exactly what you're getting. Well, most of the time, anyways.

Despite a few hiccups in the system, everything about McDonald's, from their golden arches to the menu, has stayed the same for decades. That means there has been a lot of time for hungry customers to experiment, and find ways to guarantee they get the best experience possible. It's not cheating the system, more like using it to your advantage!

Take the Filet-O-Fish for example: it uses a steamed bun that's softer and fluffier than the regular burger buns. Clever foodies have started requesting these buns instead of the regular sesame seed-topped version for years. Some people have even discovered secret menu items that you can request.

One of the most popular unofficial dishes is the grilled cheese sandwich, made from two burger buns flipped upside down. Some customers even go the extra mile by ordering a McDouble and substituting ketchup for all the missing ingredients of a Big Mac (this trick saves you about $2 at most locations).

But now a tip from an in-the-know McDonald's employee reveals how you can guarantee your order will come out of the kitchen fresh and fast...

In a post on Quora, Kamran Adan explains that you should always ask for a receipt for your McDonald's order.

Adan claims to have experience working at several McDonald's locations in London, England, and says that employees "will be immediately alert" if you request a receipt. That's because it's a habit associated with "Gapbusters," or what we call Secret Shoppers here in America.

These customers are paid to test the quality and service at a fast food location, and they need to keep a receipt to be reimbursed for their meal. Basically, employees and managers are trained to be very careful with your order if you say you need a receipt, so you should use this to your advantage.

It couldn't hurt to try, since the best case scenario is you will get fast and friendly service, with no extra cost for you. For best results Adan recommends using this trick at peak hours (12-2 p.m. and 5-7 p.m.) when employees are on the lookout for Secret Shoppers.

I'm definitely going to try this from now on!

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[H/T: Fox News]