"Take your time. I'm not in a rush."
This one is great for the grocery store, the takeout burrito restaurant or anywhere else that involves really tired people trying their best, even as they fumble and flail. For example, the woman in front of you pays the cashier but then has to rifle through her overstuffed wallet to put away the change, then store the receipt, then mash the whole fat leather money accordion into her purse. She will usually complete this action with frantic fingers because she knows she's delaying the whole line; she knows everybody just wants to go home; and she knows she should not save old, mostly-used-up gift cards with 63 cents on them. Telling her to "Take your time. I'm not in rush" always sets off the same reaction: first, surprise (really? because everybody's in a rush...) and then a flash of sweet wide-open relief. You have just given somebody a three-minute holiday, not from the stress of life, but from the stress we put on ourselves.