An old retired sailor puts on his old uniform and goes down to the docks once more for old time's sake. He hires a prostitute and takes her up to the room. He's going at it as best as he can for a guy his age and asks, "How am I doing?"
The prostitute says, "Well, sailor, you're doing about three knots."
"How's that?" he asks.
She says, "You're not hard, you're not in, and you're not getting your money back."