A little old lady went into a grocery store and put the most expensive cat food into her basket. She then went to the counter where she told the checkout girl. "Nothing but the best for my cat!"
The checkout girl said, "I'm sorry, but we cannot sell you cat food without proof that you actually own a cat. A lot of old people buy cat food to eat for themsleves and our manager wants proof that you are really buying the cat food for your cat." Perturbed, the little old lady went home, picked up her cat, and brought it back to the store. The checkout girl then sold her the cat food.
The next day, the little old lady went to the same grocery store and bought 12 of the most expensive dog cookies. "These are for my dog, one for each day of Christmas. Nothing but the best!" she exclaimed. The checkout girl refused to ring up the order. She demanded proof that the little old lady actually owned a dog, claiming that old people sometimes buy dog food for themselves to eat. Frustrated, the little old lady went home, got her dog, and brought it to the store. She was then allowed to purchase the dog cookies.
The following day, the little old lady brought a cardboard box with a hole in its lid into the grocery store. This time, she went directly to the checkout girl and asked her to stick her finger into the hole. The girl said, "No, you might have a snake in there." The little old lady assured her that there was nothing in the box that would bite her. So, the checkout girl put her finger into the hole, pulled it out right away, and shrieked, "Hey, this smells like..." At which point, the little old lady politely interrupted with, "Now, my dear, will you please sell me three rolls of toilet paper?"