A slap in the face.

I was the third person standing in line at McDonald's. Between me and the counter, a woman, a man and a 10 dollar bill sitting on the floor. I knew the bill wasn't mine, but who's bill was it? Was it the man's, or the woman's? The guy was first in line, he had just paid for his food, so it was logical to think that it was his money. The woman was second in line but closer to the bill. To my surprise, none of them had noticed the money on the floor.
Here I am, thinking of a solomonic solution to the problem. Who's money is it, and if I pick it from the floor, to whom should I offer it? Should I just wait for them to leave, pick it up and give it to the cashier? But it is not her's either, and Mr. McDonald doesn't really need another 10 bucks, does he?
After a couple of minutes they both left and the bill was still on the floor. It was my turn to walk to the counter, but before I gave my first step, the woman behind me walked forward and picked up the 10 dollar bill. I got upset, I knew it wasn't her money! But before I continued my trail of irrational thoughts, the woman walked forward and put the money in one of those charity boxes on the counter. It really felt like a slap in the face for starting up the judgmental machine we all carry in our heads. And why the hell didn't I think of that!
-"That was very nice." - I said to the lady. With a smile she replied, -"It is better than keeping it."