When I go to pay the cashier asks if I want to donate to charity. I tell her no, sorry, I don't have enough cash for that today, handing her my ten.
As she goes to put it in the till, she rolls her eyes(!) and mutters to the other cashier, "It's ONLY a dollar."
"I know right?" is the reply.
She turns back with my handful of change and I say, "I know it's only a dollar, but I'm short on cash right now."
She gets the deer-in-the-headlights look, but half-sneers, looking down at my wallet (still open so I can stick the change right in the coin pocket right away) and replies, "Why not just use your credit card? THEN you can donate."
"No thanks." I took my change and left. Not epic failure, but still pretty rude. I understand you have to ask everybody and it sucks, I used to do it, but don't try to guilt me into it.