After a long, busy day at work, Jason was finally going home. He was tired. He wasn't thinking about anything special.
"Perhaps I should go into the supermarket in our neighborhood, and pick up a couple of pounds of strawberries," Jason thought.
While Jason was driving to the store, his car phone rang. It was his wife, Jenny.
"Jason, where are you? Last night you promised to come home early to help me prepare the food and decorate the house. You know that we're having a party tonight."
"Oh, no!" Jason said. "I had so much work today that I forgot about the party."
"I know it's always a good idea to remind you to come home early, even when you promise," said Jenny. "However, this time I expected you to remember."
At first, Jason didn't understand what Jenny was talking about, but then he remembered: Jenny was having a party for him that night. It was his fiftieth birthday!