shanks' mare

Etymology:

• The expression -- believed to be Scottish in origin -- derives from shanks' nag, referring to the use of shank to refer to the part of the human leg between the knee and ankle. One theory cites "shank's mare" derived from a horse-drawn lawn mower, manufactured by Shanks & Company Ltd. which required that the human operator walk behind the device to guide the horse; however, references to the phrase in Scottish literature pre-date the existence of the Shanks lawn mower.