Which is English? "sick as a cat" / "sick as a dog"? "duopoly" / "biopoly"?

I found this game "Which is English" and it became  a  funny way to get in touch with some expressions.



Real words are mixed with fake words and expressions that are better learnt when we are among a culture where English is spoken.



Why do we say "wife and husband" instead of "husband and wife"?

I have no idea.