An old retired sailor puts on his old uniform
and heads for the docks once more, for old times sake.
He engages a prostitute and takes her up to a 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 prostitute replies, 'Well, 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 your knot getting your money back.