Photo Credit: Courtesy of 3DStockPhoto (
like image)
The original expression "sweat like a pig" allegedly comes from smelting pig iron (which sweats as it cools). Pig iron, by the way, is so named because it's shaped in molds that branch off like piglets suckling on a sow. (Also, minor point of fact, dogs can sweat a little bit through the pads on their feet.)