Steel monkey is a nickname used to refer to workers on high scaffolding or other aerial construction rigs. It is possible that the term developed from the similar term rigging monkey, used on large sailing ships to refer to crewmembers whose responsibilities included climbing the ship's mast.
Steel monkey Wikipedia
The term has been used as the title of a song, "Steel Monkey", by rock band Jethro Tull.
The term also refers to a mixed drink, composed of Steel Reserve malt liquor and orange juice, made popular by the rap group Battlecougar.