In the Terry Pratchett's book, 'Reaper Man', there is a passage:
Most species do their own evolving, making it up as they go along, which is the way Nature intended. And this is all very natural and organic and in tune with mysterious cycles of the cosmos, which believes that there's nothing like millions of years of really frustrating trial and error to give a species moral fibre and, in some cases, backbone.
This is probably fine from the species' point of view, but from the perspective of the actual individuals it can be a real pig, or at least a small pink root-eating reptile that might one day evolve into a real pig.
I'm reading this book in English, in Polish and in Russian at the same time. And I didn't really think of this phrase while reading in English, but then I noticed that translators understood it differently. The Russian one took it literally. But the Polish one translated this bold phrase as something like a 'dirty trick'. I couldn't find anything about this being an idiom, though.
What do you think? Is one of the translators wrong or is it just possible to understand it in both ways? Thanks for any help.
Best Answer
Although I can give you a bunch of links showing it being explained or used, I unfortunately can't find an "official" one explaining the meaning or origin. Here are the links I was able to find:
The Curious Incident 13 - Genius
Yahoo Answers question referencing the book The Curious Incident of the Dog in the Night-time, which also used the idiom.
Forum thread asking about idiom meanings, including this one.
Essentially, it's a British English idiom, and is a slightly shortened form of "a real pig of a day" essentially meaning a day which was utterly terrible. In the context Pratchett is using it here, it's saying something along the lines of "a really, really bad thing."
Edit: As NVZ pointed out, this is a general idiom of "a pig of [something]" meaning "a difficult or unpleasant thing or task". (Oxford Learners)