An old man went in to see the doctor and said,

"Doc, I'm turning eighty 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."

The doctor writes up a prescription for Viagra and hands it to the geezer.

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."