My tall (small) coffee is a treat very occasionally- I don't want to pay for the next persons giant whatever
I had it happen and I graciously said " thank you"- paid a good tip but declined to continue it
I think it's a THING Starbucks workers have started
It's not a thing Starbucks workers have started, I've been paying it forward for years and I rarely (like once a month) go to Starbucks.
I have had this done for me and had no idea in the world it was supposed to be a "chain" because it makes no sense. I went to work and enjoyed my day. Then the following week I did it for someone else.
I truly hope he didn't then feel obligated to keep it going right then and there, because I just wanted him to have a nice day - not take a gamble on whether or not he got a discount on his breakfast. I heard the news story and I was all

.
It's not supposed to be a chain, it's just something one person does for another, if it continues on down the line then great, if not then great.
I've done it before. I don't know what the outcome was. I've also had it done for me before, but when I asked the barista what the person behind me ordered, the bill was $28.00.
In the instance that order is much more than one would wish to pay you could simply hand them $5 and say "please put this towards the bill of the car behind me" and they will happily do so.
I've done this many times, usually just as I cross the toll bridge, I give an extra $5 and tell them I'm paying for the car behind me, usually I get a thumbs up and a happy smile and wave from the recipient behind me, I have no idea if they pay it forward but it's just a fun thing to randomly do, hence the term Random Act of Kindness.
I had a gentleman behind me at the grocery store pay quite a large portion of my bill one day, I had no idea he had done it, I slid my card through the reader, and suddenly the total was $70 less than it had been, the cashier told me what had happened and I cried, thanked the man profusely and left. He said he didn't want anything in return except for me to help someone else someday in the future when it was feasible for me to do so. At the time this happened I had just gone back to work after having been unemployed for almost a year, my savings was gone, my unemployment was running out, these groceries were taking the rest of my cash, I knew I'd be OK because I was working again but that really took the pressure off in a huge way.
I've never over thought this and it seems like people are now, it's just a RAoK, random being the key word. If others choose to continue to pay it forward then that's up to them but I honestly wouldn't have any issues saying I didn't want to pay for the next order, and if the cashier actually asked me that I'd be more inclined to say "No thanks, this was a great unexpected gift though so thanks!". Of course I'd pay it forward in another way another time.
