I have been told that the hook was the tool uaed by dockers in handling goods on the quay, and the slinging of it was when a docker who had not been employed that day hung it over his shoulder and went off to a day without work. I was told by a Londoner who was living in my place, and was wont at times to tell me to depart her presence.

Docker's Hook

It seems there is a market in the things!