Some of you have heard me tell this story.
When my son was about 7 or 8, we were getting slurpees at 711. We'd recently seen the latest Star Wars movie and he was right into it at that time.
I paid for the slurpees and the cashier put the change in my hand. I looked at it for a second, then saw that he had shorted me a fiver. I put the money on the counter.
"Excuse me." I said politely. "I think you got the change wrong."
He was trying to move to the next person in line and curtly said, "No. It's right."
I waved a hand at him, Jedi like, and said calmly. "You gave me the wrong change."
He stopped and looked at the change on the counter.
"You're right. I owe you five dollars," and he opened the till and passed me the bill.
The look on my son's face was utter amazement.