Drive-thru windows of fast food restaurants all over America are reporting a new sharp rise in a new trend - Customers 'paying it forward', meaning that they pay for the purchases made by the car right behind them. Why? Because they just want to perform a random act of kindness.

What's even more interesting is that in most cases, this one act of generosity leads to a chain reaction from everyone behind and only stops when there is no car left to pay for! One of the longest such 'pay it forward' reactions was reported in December 2012, by donut shop Tim Horton's In Winnipeg, Minnesota when 228 consecutive customers paid for each other. In April this year, burger joint Chick-fil-A reported a 'pay it forward' chain that involved 67 cars.

Then there was Wendy Clement of Amesbury, Massachusetts who started the generosity train by paying $12 for the car behind her at Heav'nly donuts where she had pulled in for a coffee. While that was certainly generous, the act was even more heartwarming given that Wendy was unemployed at the time. But her random act of kindness did not go unrewarded. It began a chain reaction that involved 55 cars, far surpassing the donut shop's previous record of 20. And it would have probably continued for even longer, had there been more cars in the drive-thru lane.

This phenomenon is not just restricted to the USA. It has also spread to neighboring Canada. Earlier this year, a young man walked into the Edmonton store of Tim Hortons and ordered 500 cups of coffee for a total of $850 CAD. The coffee of course was not for him, but for the next 500 lucky customers that walked into the store. As the news spread, it triggered a chain reaction of similar proportions. Later that week, the same generosity was bestowed upon coffee drinkers in Red Deer and Ottawa, as well as, at a coffee kiosk inside a hospital in Edmonton where a man dressed in hospital scrubs donated $500 CAD. That same afternoon, a woman whose family member had been taken care of really well, added another $800 CAD.

And it did not stop there - On Friday morning, a regular at a Tim Hortons in Calgary decided he wanted to join in the giving with another 500 free cups of coffee which in turn encouraged a local radio station to request donations from their listeners - The result? 785 additional free drinks!

So why are people doing this? The reasons are countless, from sharing good fortune to celebrating a recovery from a deadly disease to simply, wanting to bring a smile on a stranger's face! The amazing part is that most of these donors do not want to be recognized for their good deed, which is the reason they are being increasingly performed at drive-thru windows, where it is too late to thank anyone since they have already driven away - The only thing left to do, is to 'pay it forward'!

The good news is that not only does it make someone's day, but according to researchers from the University of California, Los Angeles and the University of North Carolina, random generosity also makes the giver much healthier - A true win-win for all.

Resources: nydaily.com, dailymail.co.uk