So on the tour bus of mental health patients, there was a deaf man. Since I can't speak any sign language and he couldn't lip read or speak, we had a very difficult time communicating. First he wanted to buy two t-shirts; after I wrote down the price on a piece of paper, he decided to just get one. (The price was also written on the shirt's tag, but I guess he couldn't read it.) Explaining the additional tax charges was difficult, but eventually I got the money from him and finished the transaction.
About an hour later, the group leader brought him over and explained that he needed to return the shirt because the man had spent his dinner money. Fair enough. I started to process the return when a woman picking out presents for her grandchildren behind me called out, "Oh, just add the shirt to my tab." So I give the guy back his money and hand him his shirt while the group leader spends the next several minutes explaining what happened. I'm not sure the deaf man ever fully understood - he didn't thank the woman at all. But she didn't mind - she went right back to shopping for her grandchildren. It was just really sweet of her to help out a stranger like that. If I could have, I would have given her a small discount on her purchase (she ended up spending over $100) but I don't have the authority to do that.
But thank you, anonymous lady, for inspiring me to be better with your kindness and generosity.