Three Knots

Norman, an old retired sailor, puts on his old uniform and 

heads for the docks once more, for old times sake and some 

hot sex.

He engages a lovely 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 Norman, ya 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.'

Thanks Dan !