[Sparkologist]

The old Admiral goes into a bar and meets a Prostitute.
After a few drinks she invites him back to her place, which is up several flights of stairs.
Finally, puffing and panting, he is in her bedroom and they get down to 'doing the business'. He says to her, "How am I doing My Dear, How am I doing? "
She says, "You're doing three knots, Admiral."

He says, "What do you mean My Dear. What do you mean?"
She says. 'You're not hard, you're not in, and you're not getting your money back!