A man shopping in a supermarket took his purchase of two cans of dog food to the checkout counter. The cashier asked, “Sir, do you have a dog?”
“Yes.” replied the man.
“Well, where is it?” asked the cashier.
“I left him home.” he answered.
“Sorry,” the cashier said, “You can’t buy the dog food if I can’t see the dog. That’s the rules.”
The next day he returned to the store and brought some cat food to the checkout. “Do you have a cat?” asked the cashier. “Yes,” he said, “but I left him home.”