Swing the lead
To swing the lead means to malinger or shirk work and this usage and meaning dates from the early 20th century. Some sources maintain the origin is nautical and derives from the practice of taking depth soundings using long lines weighted with lead. Sailors, or so the story goes, would swing the lead lines, pretending they were hard at work. There are two problems with this. Firstly, depth soundings were important for a ship’s safety and were closely supervised by ships’ officers who would be unlikely to allow shirking or malingering. Secondly, and perhaps more damning from an etymological point of view, the practice of naval depth sounding with lead lines went on for at least 200 years before the expression swing the lead was first cited. The mystery deepens when the OED maintains that to swing the lead dates from long before the early 20th century and in fact means to tell a tall tale with intent to deceive. It goes on to admit that the connection with malingering is not clear. Swing the lead has also been cited as an army expression for malingering dating from WWI, but supporters of the naval origin maintain the army merely borrowed the expression from the navy. Whatever the case, the jury is still out and the origin remains obscure.