An old man went to see the doctor and said, "Doc, I'm turning 80 tomorrow. I've hired a hooker for the night, and I'd love to do it just one more time before I die. Can you give me something that'll get me up?"

The doctor smiled. "I don't normally prescribe this stuff, but I think in your case I can make an exception for one night."

Later that night, out of curiosity, the doctor phoned the elderly man and asked, "How's it going?"

"Fabulous," the old man said. "I've come three times already."

"That's great," the doctor said. "the hooker must be astounded."

"Not exactly," the old man said. "She's not here yet."