He is a sexist 'pig'. = He is a 'male chauvinist pig'. [=he is a man who thinks women are not equal to men]
The train station will be renovated 'when pigs fly'. [=it will never be renovated]
“This time I think he'll ask me to marry him!” “Yeah, and 'pigs might fly'.”
(..) In the meantime, it is up to us to decide what to do. I'm listening. Say something interesting. You heard what he said, how the little pigs will grunt when they hear how the old boar suffered. So now we're grunting. So what? We want blood-revenge against Aelle? - Yes. (..)2017 TvShow: Vikings Title: The Great Army Season: 4 Episode 17