Card Catastrophe
It’s very frustrating if you’re trying to do something nice for someone and it totally backfires—your attempted good deed ends up blowing up in your face, and you might get in trouble for it when all you were trying to do is be kind.
But it might even be worse if you weren’t really trying to be kind; you were just trying to get the lady in front of you to hurry up with her groceries so you can get through the line. At least if you were trying to do something nice, you could feel good about yourself, even when things go wrong. But if you weren’t really trying to be kind, you don’t even have that small comfort.