Have you ever been in one of those "pay it forward" lines at a coffee shop? The barista tells you your cup of coffee has been paid for, so you offer to pay for the person behind you, and so on and so forth.

McDonald's is taking the "pay it forward" line to the next level, handing out 500 "McCafe It Forward" cards across the country. Here's how it works: If you receive a card, you get a free small cup of premium roast coffee or one iced coffee. Then you pass the card along to somebody in your life you think deserves a free coffee — a friend, a stranger, whoever — and they get their free coffee and pass the card along. The deal runs through Friday, Aug. 23 at participating McDonald's restaurants. 

One of the coolest aspects of the campaign is that you can follow along with where the cards are being used: 

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