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'.”
(..) ...and we'll spend the rest of our lives in total silence. It worked for my parents. - Hi, guys. - Oh, hey. I need guinea pigs. Okay, there's a lab animal supply company in Reseda you could try. But if your research is going to have human applications, I suggest white mice. Their brain chemistry (..)2007 TvShow: The Big Bang Theory Title: The Grasshopper Experiment Season: 1 Episode 8