A young man was walking through a supermarket to pick up a few things when he noticed an old lady following him around. Thinking nothing of it, he ignored her and continued on. When he reached the checkout line he realised the old lady was in front of him in line.

“Pardon me,” she turned around and said to the young man. “I’m sorry if my staring at you has made you feel uncomfortable. It’s just that you look just like my son, who just died recently.”

“I’m very sorry,” replied the young man. “Is there anything I can do for you?”

“Oh, yes,” she said. “As I’m leaving, can you say ‘Goodbye, Mother!’? It would make me feel so much better.”

“Sure,” answered the young man.

As the old woman was leaving the young man called out, “Goodbye, Mother!”

As he stepped up to the checkout counter, he saw that his total was $150.

“How can that be?” he asked, “I only purchased two things!”

The clerk shrugged in confusion, “Your mother said that you would pay for her.”