This creates these annoying lines where everyone feels morally obligated to pay for the person behind them. And it totally takes away the spirit of the gesture, because then absolutely no one gets a free drink except for the one guy at the end who doesn't want to keep the train going, so then he's like the jerk of the train *any* is the only one who ever benefitted from the whole entire thing.

So basically the guy at the front paid for the guy at the back, only really inefficiently and annoying all the workers.

Just take the first free drink in the spirit it was given. Pay it forward in some other way at some other time.