This expression is my rhyming slang version of a term used by people at the Department of Conservation's Glenorchy field centre in the mid to late 1990s when I worked there as a hut warden.
The meaning and etymology of the underlying expression will be well known to many current and former employees of the Department of Conservation. It is a sibling expression to "shiny arsed seat warmer". Its meaning is 'inadequate, useless, not up to standard, lacking virility'.
I first used the term to describe the standard of environmental assessment carried out by the Otago Conservancy for the Harris Saddle shelter proposal.