Norman, an old retired sailor, puts on his old uniform and heads for the docks once more for old times sake.
He engages a woman of the night and takes her up to her room.
He's soon going at it as well as he can for a guy his age, but needing some reassurance, he asks, 'How am I doing?'
The lady smoothly replies, 'Well Norman, you old sailor, you're doing about three knots!'
'Three knots?' he asks. ' What's that supposed to mean?'
She says, 'You're knot hard, you're knot in, and you're knot getting your money back!!'