After a lengthy tour of sea duty, an old sailor finally gets some shore leave. Fortunately, a nearby brothel had been recommeded to him by some of his younger shipmates.
The old sailor walked over to the brothel, where he chose his girl and began. "How am I doing?" he asked her.
"Three knots," she replied.
"Three knots? What does that mean?" asked the sailor.
The girl answered, "You're not hard. You're not in. And, you're not getting your money back."