Something you need to know in order to appreciate this story ... Subway offers up daily deals. With each day of the week, you can get a 6" sub combo meal (sub, chips/cookies/soup, soda) for $4.29. For example, Wednesday is turkey day so you can fork over $4.29 and get a 6" turkey sub, chips and a soda.
I do this basically every Wednesday.
Today is no different. I hit subway to get my crazy bargain. I notice the woman in front of me is also here to cash in on the deal. She's getting a 6" turkey sub. One problem, though. She gets to the cash register and the dude asks "Do you want to make this a meal?" She replies "Nope, just the sandwich and chips." I consider speaking up, but I don't. Dude rings her up for $5.04. She pays and leaves. I then pay $4.29 for the same thing she got, but I received a soda in addition to the sandwich and chips.
Here's another way of looking at it.
The woman in front of me paid 75 cents so that she didn't have to be bothered to receive a soda and then throw it in the trash. She paid Subway to keep one more soda in their inventory instead of giving it to her.