An old man limped into the doctor's office and said, "Doctor, my knee hurts so bad, I can hardly walk!"
The doctor slowly eyed him from head to toe, paused and then said, "Sir, how old are you?"
"I'm 98," the man announced proudly.
The doctor just sighed, and looked at him again. Finally he said, "Sir, I'm sorry. I mean, just look at you. You are almost one hundred years old, and you're complaining that your knee hurts? Well, what did you expect?"
The old man said, "Well, my other knee is 98 years old too, and it doesn't hurt!"